My bf's condoms keep breaking and I don't know what to d

I (19F) have been with my bf (20M) for 9 months now. We began being intimate about a month into our relationship and since then I'd say we've broken probably around 10 condoms during sex. It doesn't seem like a lot over 8 months, but considering that they're not supposed to break easily and we only have sex about once a week, it's making me kind of concerned. I don't understand why they keep breaking, we've tried different types, different sizes, different brands but eventually one always breaks.

I don't think he's tampering with them, like the last time it happened he opened a new box in front of me and it still broke. I also don't want to go on the pill because I don't want to take anything that affects my hormones. I also don't want to keep having to take plan B either. Any advice on what I should do, and also any advice how to make them not break?

Edit: Hi guys, I've had a lot of people telling me to just go on the pill, but I've already stated that I don't want to for my own personal reasons. Thanks to those who suggested non hormonal birth control, I'll keep it in mind as a last resort but I hope to fix the issue without doing things to my body. As many of you had suggested, I'll look into things like proper lube, correct sizing and making sure he's putting them on properly.