What do you think is he up to?

So I met this guy a year ago, we were dating but we're not officially together. We never talked about it, he never asked nor did I. At first I really though I was just his call but somehow I felt and I know that he has feelings for me too. I liked him the first time I saw him..and actually I am inlove with him. I was so confused about his feelings for me, I tried to stay away from him and move on but just once call from him and I would go back exactly where I was before. The last time we spent time with each other was september of last year. After that he moved to another state and I went to vegas for school. I know he's very busy and focus on his studies(he's med student in sf and after he got his MD that was the time he moved back to his own state) although he told he'll come back in sf after one year. When he left he told me we should stay in touch. I didn't expect him to keep his promise so I tried so hard to forget him. Two months ped and I got a message from him, asking like how are you? are u still in vegas? do u have a bf? I said I'm still single and then he said maybe he could visit me. Again I didn't want to have high hopes about it, but then weeks after weeks he would check on me again and remind me about his visit and one time he said maybe I should visit him too. We has the same conversation every month until now, and I can't help myself not to be happy about it. I feel like maybe we still ahve a chance. But then valentines day came, I texted him and I got nothing. Usually he would respond after a few minutes whenever I text him. This made me feel more confused, I though maybe he really has a gf and they're togther so he didin't text back. I( asked him before if he has a gf and he said I am his gf.Now I'm thinking maybe I was just a fling to him. BUt why would he waste time talking to me and planning about vsiiting each other if he has a gf? He knew he told me that he's taken I wouldn't bother to stay in touch with becuase I don't want being the third person but he said he's single..Please can somebody tell me something about what this guy is up to? did u have he same expereience? Do u think he has feelings for me?..I'm so upset not gettinga any resposne from him when I greeted him a happy valentines..I was 19 and he was 24 when I met him..but I wasn't not like the other teenagers who are just after and curiousity. I just turned 20 and I know I'm matured enough for my age but right now I don't kow what to do. Should I keep waiting or should I just move on no matter how hard it is..