Please help me

Okay, so I've been dating my boyfriend for 3 months, I actually never felt this way about a boy, I can tell you that before he came into my life I never felt really happy, but he changed things, the thing is my mom hates him cause she got a call from a random person, that person told her that he's bad influence cause he smokes weed and he's not studying right now... I know that he's not bad influence cause I smoke weed too and I don't see anything bad in it.. Plus he's a very very good person and I know he would never do something bad to me... I'm 17, we're the same age, and I know I'm too young and maybe I don't know a lot of things, but  I really want to be with him, I can't even see him now cause my mom won't let me go anywhere... I'm depressed and I just really don't know what to do right now...