Am I stressing myself out for nothing?

This past weekend I lost my virginity with my boyfriend. We had sex 4 times total, every time with a condom, but the last time he came inside of me (with the condom on). He pulled out immediately after he came which I appreciated but I’m still anxious that I could get pregnant. I started my birth control pills 2 weeks ago, so I know they are effective, but I just need people who have been in this position to give their input. Last thing, I have had to pee more than normal, is that something I should be concerned about or am I over analyzing? I’m just trying to figure out if it’s worth it to purchase plan B if we were cautious.