Advice and options

I was on BC for less than 9 months and I gained weight like crazy, so I stopped taking it. I would really like to have sex with my boyfriend instead of being scared of getting pregnant. Now him on the other hand disagrees with anything being inserted but he refuses to buy condoms. I’m hoping I could get some other options and/or advice from everyone else that has experience with IUD, the ring, etc. What would be better? Any discomfort?