Confusion sets in...

I am not a creeper and I am not desperate...but all of a sudden, I feel like that is how I am going to come across when trying to figure out how to interact (or not interact) with someone...
I don't actually know what I'm doing. I'm not usually this unsure of myself. I hate that I am allowing someone else to make me feel this uncertain.
I'm sure by now, that you have all figured out that I am talking about someone of the opposite sex. I am not in a relationship with this person, but I would like to see if a relationship of any kind is a possibility. With this interest, all of a sudden I become an insecure, silly girl. That just pisses me off...
I should be confident and sure of myself. I know I'm a great person, but all of a sudden I'm saying to myself, self, if you text him too soon it will look like this, or if he hasn't called to see if you want to do anything, he isn't intersted, and if you try to initiate you will come off very desperate and he won't want anything to do with you...What is wrong with me?! Does this happen to everyone? I hate that a very random situation with a very random person has turned me into this person who is very unassured...I just want to know where to go from here, if anywhere...
Does anyone have an answer...?!