contraception help!

so my boyfriend is allergic to latex, and he's also 12.5" when fully erect, so buying condoms is a little hard. I'm currently not on birth control (I eventually want the implant, but because I don't have health insurance right now, I can't afford it). I was looking up female versions of contraception, but they all seem to need a prescription, or aren't as effective. have any of you ladies used a combination of several (such as female condom and spermicide)?