Condom Broke 😰

I'm 17 and have been with my boyfriend for 9 months now. We just started having sex a few weeks ago and it's been great. I'm on birth control and we use condoms but last night the condom broke. We talked about plan b but decided against it since I'm on birth control and take it the same time every night. I love him so much but I'm not ready to have a kid yet. I'm really anxious that I could be pregnant. It's not very likely but my luck is not good. I get my period in around 3 weeks. What are your guy's thoughts? The condom has broke for us twice now. This first time he hadn't finished yet. How could we prevent this from happening again? Any advice would be greatly appreciated!