GalwayGirl, if you already have some Slynd, I would bite the bullet and take it for a week or so then stop to provoke a bleed. It will probably be a heavy bleed.
You definitely need to look at other progesterone options but you might find the Slynd (drospirenone) is tolerable. Angeliq oral HRT (which I found tolerable but progesterone heavy) contains Slynd but interestingly, the progesterone dose is 2mg in Europe but only 0.5mg in the US (both versions contain 1mg oestrogen) so I would probably aim to take something like 1mg every day on a continuous combined basis. No way do you need 4mg every day unless you are on a mega dose of oestrogen or have an ongoing problem with womb lining build up. Obviously you will have to cut the tablet into four.
So to recap, I would take the full 4mg dose of Slynd for at least a week and more if you can, stop taking it, have a bleed and then start taking it again every day at all reduced dose. I would be aiming at around 1mg per day if you are severely progesterone intolerant and I would also have a transvaginal scan in a few months to check it's a high enough dose of progesterone.
I hope that helps.