It's not just a girl thing....
I have battled the tendency to put on weight my whole life. I was fat as a little kid and as I got older I became involved in sports so I was always able to "diffuse" the problem with all the excercise. I would eat about 5,000 calories per day, and not get fat. I was that active. As I got even older (after college), the excercise diminished due to working, etc... and that is when I started to gain weight. I know the feeling, you get sluggish and your energy level is not the same. You say you weigh 145-150. My question to you is, what is the weight you are used to carrying yourself at? If it is less than that, then I can see how you would feel "fat". As far as actually being fat, I don't know how tall you are, but even if you are only 5'2", the weight that weight watchers sets as a goal is 135, so, my dear, you are not that far off from a desirable weight. I wouldn't worry about it too much. I find that the more you worry about it, the more you eat and there starts a vicious cycle. So as Bobby McLearen once said... Don't worry... Be Happy!!!!
Just for the record, I am 6'5" and weigh about 270. I consider myself about 30 pounds overweight, and I AM doing something about it.
Hope this helps