Relationship help. Cheating?
So me and my boyfriend have been together for 4 months. About a month ago I found in his phone messages to and from a girl like flirting and "hitting it". I did not confront him about it that day but the next day he sent me a pic of an earring he found in his car, which was not mine and I said "why dont you ask michelle" which is the girl. He said it was him and his friend texting her just messing around and he told michelle just to stop texting him after all this happened. We worked it all out and are good now. Well recently I saw him on twitter retweeting and favoriting a lot of some girls stuff. I know this is bad, but I looked in his messages and the girl said "you should text me" and he said "whats your number" and she didn't reply so he said again "that number though?" And she gave it to him. I also saw that he has favorited 3 of her pictures on twitter too. I mentioned something about her and he said he didn't even have her number. I looked on his phone and her number & messages were deleted out of the twitter messages and no where in his phone. Also he was just casually talking to a girl on twitter (which I knew he used to have a thing with) and she said for him to text him and he got her number too. I also so on Facebook him say to a friend (this conversation was in out first month of dating) that said "i have a great gf and talking to a few rebound chicks on the side. You know how it is" and the guy said "yea man gotta spread the " and my boyfriend said "lol pretty much" uhhh like what does that even mean? I know my boyfriend loves me very much and I love him and we even talked about when I graduate in 2 months for us to maybe get an apartment together at the end of the year or he will wait in my city till id be able to. So it is pretty serious. Im just so confused about everything and don't know who to talk to about this. I love him so much and don't want to lost him. Oh and also next month he is going to panama city beach for spring break with all his friends, and I'm worried considering there will be soooo many slutty girls there and he will be drunk.. im also going there with friends over summer though but I know I won't do anything wrong.. am I just over thinking all this and worrying too much or no?