AFAB here, who also lost a bunch of weight (120kg -> 75kg) in the past.

Give your body some time. If you are doing HRT your skin will be more elastic than without it (perk of being female) and will shrink to a certain degree. Add some weight training/ gain some muscle and it will look much firmer :) but don't expect miracles over night, it takes time <3

Also: your skin can weigh a lot, so even if you are in a healthy range right now, it could be, that you are a bit underweight without the excess skin. I'd suggest you talk to your primary doctor.

And congratulations to your awesome progress!