Affiliate Marketing Secrets

Now a junior in high school, I am around people every second who I have affiliated my self with at some instance and I am at the point where I am not sure if I am a socially awkward person or just naturally quiet. I have no problem going up and presenting in class (though a bit shaky or nervous) or greeting people and starting small talk but after the small talk on my part with fellow peers, I tend to lose the ability to keep a train of thought going. I just stop talking as if I never had in the first place. I feel weird about doing that but I have nothing else to talk about. With my girlfriend, I am not like this nor am I with certain groups of friends but others whom I have known and hung out with for a few years now by playing football I tend to not be the most social and I dont mean to come off as weird or anything. I tend to feel like I am almost trapped with my football team, that is some people, and I shouldn’t feel that way at all. My question is, do I exhort signs of social awkwardom or am I just a quiet person? If I do, how and when will I be able to overcome that obsticle?