By doing the "girly pushups" you aren't getting the full effect from the workout as it changes the centre of gravity of your body making it much easier to do (as you already know),
i guess if you don't have much upper body strength girly pushups are alright, but you should switch over to proper pushups , doesn't matter if you only do 10 pushups to start with , just work your way up , each day add an extra one pushup. It's much better to do 20 real push up then 100 girl pushups, as when your developing intensity is most important
hope this helps