Am I being too sensitive?

There is this one girl at my highschool that I've liked for a while. Recently, I've found out that she likes me as well. We went to a formal dance together and it was wonderful. We held hands, danced, and what not. Before we went to the dance together we talked and texted each other a lot. However, after the dance she has not talked to me as much. In addition, I've started becoming jealous when she starts talking to other guys. Whereas, before I didnt mind her talking to other guys at all. Also, when I notice that we don't talk to each other as much I get very sad and upset - you can say my feelings are dependent on how she treats me.

I do not understand why this girl that I like does not talk to me as much anymore. Am I being too obsessive and sensitive? How do I stop thinking about her? I like her and most of the things that she's done supports that she likes me as well. I want to "be official," but this is what's killing me.

I am not an expert but I would say it's a mixture of obsessiveness & sensitivity if you guys are not dating it shouldn't really matter if she talks to other guys if you really do like her try telling her so you know even if she does talk to other guys after everything else you're the one she's with besides girls like guys that are sweet but not VERY sensitive.