I believe my 2 year old kitty is pregnant...?

At first, I noticed that it looked like she was getting milk in the nipples closet to her tail. Then I noticed her nipples were pink. Just this past week, she was lying out on the floor and I noticed that she has a lil bigger belly then her normal self. So, i held my hand on her belly and after some time, i began to feel little, light thumps. How far along could she be if she is in fact pregnant?