TBH there is a LOT of confusion over this even between doctors.
The regimen is 12 days per month and most specialists don't go by the 14 days on/off but suggest 12 days each calendar month.
(The 14 days on and off was suggested in GP 'training' to help women remember how to take it .)
I'm not clear where you are in your cycle.
Put it this way, nothing terrible is going to happen whatever you do over the next few days or weeks, regardless of how you take it.
And to be honest this shouldn't need a menopause clinic to sort out- it's very very basic HRT prescribing and your GP could easily update themselves with all the online guidance that's there.
You've said your dr has put you on 21 days but upthread you said 25 days. Typo?
Taking 100gms a day doesn't stop the bleeding or reset your periods. The dose is too low. It's supposed to be for women who don't bleed at all (or very very rarely.)
You could stop now and then start again on 1 June taking it for 12 days.
Then the 12 July etc.
But you have to take 200mgs not 100mgs.
Your period will come as and when, and as you're in peri may be delayed but ignore that.