Need relationship advice

My bf and I have been dating for 2 years now. We have been doing the long distance thing for atleast a year. We see each other when we have breaks from school and for 2 week long span in the summer. We talk via Skype once or twice a week and Snapchat periodically through the week. I have now recently developed a feeling that I don't know if I want to be in this relationship anymore. I only feel like this until I get to talk to him and then it goes away. I love him and I don't want to get ruin something that took 2 years to develop, but at the same time I don't know if I am happy. I am so confused this is my first relationship (I didn't start dating until I was 17). I don't really know how to go about this I am just really confused and sad. I feel guilty that I feel this way. I don't want to do anything I will regret in the end. If any one could give me some advice it would be appreciated.