Back to condoms

So after totally awful 4 month experience with birth control (already have several mental illnesses and it made them LOT worse) i think on going back to condoms, problem is - i always had pregnancy scares when using it and I don't want to feel that way again. I was paranoid that it will break, somehow sperm will get out etc. (it has never happened tho). Are there any helpful tips of some extra safety I could use?