Hi Bljezard.
I'm on femoston conti, and I did top up with Sandrena gel, but I was on 1.1/2mg, then. I used 1/2. ....or sometimes 1mg of the gel, to top up...all was great at first, but then I started bleeding, went for a scan, all was ok, so can only put it down to not enough progesterone....it must have tipped the balance...
If I were you, I'd just double up the Femoston Conti, because then at least you'll know your getting enough progesterone too.......I messed up with adding in Sandrena, the bleed was really painful too, so that's what I do now, I double up the Femoston....
Hope this helps...
Jd xx