When do you stop trying?

So throughout my dating career, I have found myself a number of times "trying too hard" in every sense of that statement. In almost every other aspect of life I tend to think of myself as someone who is very easy going and who doesn't let peoples feelings or mixed signals bother me too much. I hardly ever think to myself why does this friend not want to hang out with me, or what is it about me that makes my boss not like me, or is this friend just being nice to me because they are too nice of a person to just not be friends with me. Those are just a few examples of questions that I don't ever ask myself....except when it involves someone who I am really "interested" in, then I begin to find myself asking TONS of questions! Keep in mind it only happens when I REALLY like someone so the amount of people this has happened for is only a handful or so. Well, without revealing too much, I must say I have found myself in that predicament again! I have found myself going through entire days stewing over silly trivial things. I won't reveal all the trivial questions i ask myself so that I don't make myself look like a complete loser, but I will say, I have it bad and don't know how to read the signs or handle the situation!