Moving in together at 18?

Sooo. My boyfriend is moving in with me this August! He is gonna be 20 then and I will be 18. We're gonna live in the upstairs of my moms house and pay a bit of rent every month. We're serious and both want to eventually get married and have kids, and we will have been dating for a year by this fall. What are your opinions on this? I don't want my relationship to be influenced by other people but I would like to hear opinions or advice on living together!!! Thank you ❤