Are underwire bras bad? Are they supposed to be uncomfortable?

So I'm 15 years old and I've been wearing sports bras since I was 12. I've never worn in underwire bra. I've read online and I've heard that underwire bras are unhealthy for you and they make your breasts weaker. Is this true? I also just bought my first bra a couple of days ago and I haven't been able to wear it for more than a couple hours because it hurts. It's not too tight or too loose because my mom and the lady at the store made sure it fit perfectly. I just want to know if I'm making the right decision by starting to wear an underwire bra.