IVF advice - natural FET unknown ovulation date

[seven201]

This post is so long. If you don't want to read it all the main questions is:
How much does it matter for the FET to be exactly 5 days after ovulation? (My ovulation date or LH surge is not exactly known)

Apologies, this may be long!

Last month I had a cancelled medicated FET as my lining didn't thicken which was odd as the previous one had been fine. My doctor said maybe next time (transfer planned early oct) we'd do a natural cycle one but in the meantime to come in for a monitoring scan to check how my lining is naturally. Got a call later that day (bank hol Monday cd14) to day lining was fine and we'd probably be able to do the transfer this month and to start doing opks! What a lovely surprise. Weds (cd16) scan showed lining doing well, follicle 14. Today I had a scan and the follicle has collapsed so I ovulated sometime between the scan Wednesday lunchtime to today lunchtime with no LH surge showing up. But... on the previous Saturday (cd12 so really early for me) I did have a positive opk on one brand of cheapie opk but a different brand was negative so I decided the first brand was faulty. Even if my LH surge was actually sat surely I'd have ovulated before the Wednesday when they scanned me?

I didn't mention the rogue Saturday opk to the doctor but now feeing I should have! Doctor said I can have a transfer on Tuesday but it's not ideal as she doesn't know when I actually ovulated (she's guessing weds) and she doesn't want it to not work and then for us to think it was because we did it on the wrong day. It's our last frozen embryo.

I've had two cancelled transfers (Covid lockdown and then last month) so I am obviously keen to not do that again as my mental health has taken a battering. I had a good feeling about this go. I'm a teacher and am not in school in the lead up to transfer in case one of the hundreds of pupils who comes through my classroom develops symptoms. That is what is stressing me out so much. I've already had 3 days wfh this week but if I do cancel this cycle then I'd potentially be wfh for 3 weeks (I have longish cycles) from period-transfer next month. Obviously that is really crap for my students/school and it makes me feel awfully guilty! It will not go down well I think. I can't afford to quit my job.

My clinic closes over Xmas so I think if I have the FET this month there'd still be time for an egg collection round before then. I'm getting old so don't want to wait until next year. I am very impatient with treatment.

Doctor said I can go ahead this time or re-start next month but was leaning towards next month until I said I was stressed about having more time off. She's taken some blood and will call me tomorrow. I stupidly didn't ask what this blood test is for! In the meantime she said to start oestrogen, progesterone (suppositories and injection).

So tomorrow I have to decide. If it gets cancelled tomorrow I will be extra upset as we could have sex today just in case we're not too late for the egg. I have been naturally pregnant twice before so it's not impossible.

Sorry, that was sooo long! It's been cathartic for me!

What I would like to know is anyone know how much it matters for the FET to be exactly 5 days after ovulation? And also if anyone just has any knowledge or advice on this as I am so confused right now.

I think the bloods they took could’ve been LH and Progesteone as these can give an indication of ovulation although not the exact timing. I’ll be honest, in my clinic they would not go ahead with the transfer (and especially if it was your last embryo) as the timing has to be specific. They will only be able to hazard a guess at when you ovulated and for me that would be a big gamble. You could be potentially transferring an embryo at the wrong timeframe. I know it’s so upsetting to have cycles cancelled but I feel it’s better off in the long run. Could you perhaps do a medicated to avoid this happening again?

Thank you for your advice @AfterGlow87

My last medicated failed as my lining didn't get beyond 5mm despite upping my estrogen tablets so the doctor thought natural might be better for me. And it was finally going well. Usually opks work for me. It's all so confusing!

The window for ovulation is between weds lunch and Friday lunch so in my head they'd only be out by potentially half a day which doesn't sound too bad, but I'm no doctor! I accidentally typed weds earlier, the doctor said they'd assume/guess ov happened on Thursday to work things out. Maybe the blood test will help a little, or not.

Agh. I just hope when the doctor or nurse rings tomorrow with the blood test results they say "all looking good" or "let's not do it". I really don't want them to say it's up to me, but is a risk etc.

All my FET has been has been natural and you do need to monitor OPKS closely - mine said twice a day but they also followed up with a scan every other day and if the follicle had got to a certain size they'd give a trigger shot to ensure timing is right

To be honest I wouldn't go ahead with transfer if you have missed your ovulation and not sure when it happened as you'll just waste the embryo - my clinic said the embryo will wait for the lining but the lining won't wait for an embryo

@ivfbeenbusy thank you. I have been doing opks twice a day and had scans every other day but it was still missed. Although has to have been between weds pm and Friday am so not a huge window. My follicle was 15mm weds so the plan was to trigger me Friday/yesterday (if I didn't have a positive opk).

Agh. I don't want to waste the embryo but I am so worried about telling school that I'll be off for about 3 weeks! Blooming Covid and blooming opks!!

Ah ok does sound massively unfortunate as usually naturally ovulation doesn't happen until at least 22mm

I guess if they think they've caught it quick enough and are monitoring estrogen and progesterone and lining thickness then it might be ok but I still think it might lead to additional stress and anxiety in the 2ww

Why would you need 3 weeks off?

@ivfbeenbusy Thank you for taking the time to reply.

It is a bit odd isn't it. The nurse spent ages looking for the follicle and in the end a doctor was brought in to find the collapsed follicle. I think seeing as it was only 15mm on weds it's unlikely to have released on that afternoon/evening and would have been thurs or Friday before mid-day.

My doctor said I shouldn't be classroom based (so wfh) until after transfer as if a student in one of my classes (I see about 300 different kids over a fortnight) develops symptoms then I'd need to quarantine myself etc. So it would be from cd1 until day of transfer that I'd be off. And I don't usually ovulate until cd19ish.

My blood tests result were good (no idea in what respect, but she did mention LH) so am going for the transfer on Tuesday afternoon. The nurse I spoke to didn't seem to think the ovulation window was too wide, so that gave me a bit more hope/confidence.