Not Sure..

I've been looking everywhere, but can't seem to find the answer.

I am 20 years old. I have been on birth control (ortho tri-cyclen) on and off for about 5 years (it made my period regular). It has worked perfectly for me, as I have tried other forms of oral contraceptives. I have been taking it for about 3 years straight now and have never ran into any of these problems. I have been with my boyfriend for about 3 years now, no change in partners.

Lately I have been quite moody, my back constantly hurts, feel like I can never get enough sleep (always tired), cramps every now and then, light headaches, breasts are more sensitive, and urinating more often. I just don't feel normal.. My last period was a lot lighter than usual, and about 2 weeks after my period, I spotted. It's very light, a very light pink. It only lasts not even a day, maybe a few hours. I have not been under any stress, no more than it has always been, same routine, and I take my pill everyday (sometimes a couple hours later than my usual time).

I was just curious if there is a possibility that I could be pregnant with these symptoms. It has me worried (even though I would be more than thrilled if I were pregnant).

I know there is a very slim chance that I could become pregnant while on birth control. But could my pills become uneffective if my body is somehow rejecting them, increasing my chance for pregnancy?

Any insight would be helpful. Thank you in advance.