Is age really just a number

Daniie • DMP:)
There's this really cute guy I've been talking to well he's sorta a family friend we've been knowing each other for year and we recently had sex it was great like really great but he's 18 years old and I'm turning 21 in July yes it's not a big difference but I have a two year old little girl and I'm kinda worried maybe he's just too young to handle all of this...in need of advice