confused

I am very new to the sex life. The man I lost my virginity to had a rather small penis and kept going soft. He said he needs head first but I don’t give unless I receive so I never made him orgasm because he would get soft in between. My fb tho has a big dick and I’ve made him orgasm rather quicky. His dick rarely slips out too. I know men are different but for the first guy I am just curious to know if it’s me? And since I’m taking big dick, would it affect my vaginal walls? Would that make it feel different for a dude with a smaller penis? I just lost my virginity and I haven’t had sex that many times so it’s still pretty tight. I just want to make sure it stays tight.