Help???

I started birth control maybe 3 weeks ago, and since I started mid-cycle, it pushed my period back but this past week was the set week if I wasn’t on birth control and I’m having brown discharge now and idk what it means? Also my boobs have been rly sore and my boyfriend came inside me for the first time today and it hurt to pee after sex so idk what’s going on and do you think I’ll be safe from pregnancy since I’m on the pill :00