What has happened?

Hello. I'm 16 years old and my boyfriend is 17 years old. We had our very first time together on the 20th of August, since then I've been having some complications. My period after I had sex with him was only one day and it was very light, which was on the 28th of August. Is this normal? He was wearing a condom, but I feel like there's something wrong. Please reassure me. I've talked to family members and they've told me I'm okay, but I just wanted to be sure.

Thank you ☺