perimenopause, HRT and understanding my cycle

[Psychonabike]

I could be overthinking this, but I'm in a muddle and not sure what I'm supposed to do...

Perimenopausal for a couple of years. Went on HRT last July. Oestrogel (4 pumps) daily and Utrogestan days 15-26. Had a regular-ish 28-30 day cycle prior to HRT although I had been having two weeks of spotting leading to my period. Have maintained a 28 day cycle on HRT though the bleeding actually only really lasts 2, perhaps 3 days.

I had covid in January. My last, and now my currently expected period have been late.

So I take the utrogestan days 15-26, would usually expect my period day 28/day 1, i.e. a couple of days after I stop the utrogestan.

However, last month it was a few days late. Now I'm 5 days after stopping utrogestan and still no sign.

I'm not pregnant.

My question is:

Because I am on HRT do I always count 1-28 and keep taking the utrogestan on day 15 no matter what happens with my period?

Or do I keep counting the days upwards of 28 and consider day 1 when my period comes?

So am I on day 31 right now or day 3?

I'm really hoping you are all going to say stick to the 28 days no matter what, because I have weddings, holidays and various events over the next 6 months which all miss the period part of my cycle. If I start varying it could all be a bit shit.

Thank you!

Because I am on HRT do I always count 1-28 and keep taking the utrogestan on day 15 no matter what happens with my period?

In a word, yes.

Stick to the regime. If you were taking a pack of tablets, you'd (in theory) keep going with the pack and not delay the progestin tablets, in the 2nd half of the pack. So this is the same, except the items are in 2 different forms.

Thank you @JinglingHellsBells. That makes sense -treat it like the pill and just keep running the "packs" as they fall. Thank you. I think years of poor fertility (where identifying the real day 1 is important) have messed with my common sense.