@LittleTipple that's certainly awkward. I'm on my second cycle post mc. To calculate my first period/ovulation I did the following...not sure if this will help and apologies for TMI for non-mc people.
There was a distinct day for me when the mc had ended but I had run on bleeding. This was when the cramps had stopped and it was just spotting. I took this to be the first day of the new cycle (ie the LMP) rather than as you did calculating it from the start of the mc. I ovulated 12 days after this (+ve test). I usually have a 14 day luteal cycle but I suspect the difference here was in calculating exactly when the mc stopped, as is your challenge which is why it looks like you ovulated late.
I would err on the side of caution on your estimate, or alternatively spell this out for your midwife so she knows exactly what she's working with. If you actually had a positive ovulation test that will be the most reliable way forward, and you'll notice that there are websites that allow you to calculate due date from ovulation rather than LMP. You can change the date on your app in the settings to go off ovulation date rather than LMP however obviously it sucks to feel like you're going back in time.
@Turtle05 the only thing I've found is elderflower cordial made up with fizzy water. Gives me enough sugar to not feel grim but doesn't involve eating food first thing!
@earlybirdhasanap I see what you are saying. Equally though, from your mums perspective it may be that she would like to know either way so she can support you through these days? I have told my mum even though it's crazy early because she wants to be there through the good and the bad. She'd have been really upset if I'd covered up the two MCs before. That said, you know your mum best! Personally I've told quite a lot of people strictly outside work, mainly because they are the people I would want to talk to if it all went wrong!