Hi JudgeJudy and welcome to the forums.
The accepted recommended stocking for a normal community tanks is an inch per gallon, so with your platies and and tetras alone you are almost at the limit. You can get around this by having very good filtration (what kind of filter do you have?) an additional air pump for extra oxygen and doing very regular water changes, say 25% + a week.
If you are already doing this then you might be ok with your current stock, but I would certainly say don't add any more as that's a lot for 45 litres and mollies in particular can get very big so you might want to think about re-homing them.