Hard time with being 20.

I have been very emotional lately and very cautious of who I talk to, what I do, and so many emotions have been running through my mind and I don't no if it's because I am realizing I'm no longer a teen or if I have so much going on. I've been feeling like this dr maybe 2 months now and my boyfriend has finally said something to me. He said I'm not the spontaneous person I used to be. Has any else had a tough time with turning 20 or 30 or whatever ?