Birth control

So I’m 18 and in a few months I will be moving in with my boyfriend of almost 3 years so I’m probably gonna need some birth control because we aren’t financially stable enough to support a child rn and we’re just not at that point in the relationship so I was wondering what’s the best kind of birth control to take? I’d prefer pills or the shot but I’m not sure of the side effects and etc which is better and more effective. I’d also prefer not to be on one that’ll cause me to gain weight so if y’all could just help me out and give me your opinion and what not I’d really appreciate it!☺️