IS my cat pregnant?

Hi I am wondering if anyone can help me plz my cat was in heat nd she mated on the 28th nd 29th of dec12 she was only in heat 3days nd just stopped which is not normal for her so I thought she might be pregnant I worked her due date out to be on the 28th of Feb which is only a week on Thursday ive been reading up on pregnant cats and apart from her appreciate changing ie eating alot more, I havent really seen a dramatic change in her. The 1st couple of weeks she wouldnt even let me pick her up never mind let me touch her belly but as the weeks went on she did but she would cry. Her nipples havent gone the pinky colour there meant to or getting bigger but with her having quit alot of thick black fur its hard to see them but when she's rolling all over the floor I can see them clear as day nd shes lost her fur round them to. When I looked at her it looked like she was getting bigger but now im not to sure especially if she if nd with just over a week to go u should be able to tell just by looking at her.
The past week or so she has become a lot more loving especially on a nite. Im just not sure at all anymore nd I was wondering if someone could give me alittle bit advise thanks xxxxxxx

If she is pregnant she may be carrying only one or two kittens, but you need to take her to a vet to be sure. If she is not pregnant it would be a good idea to get her spayed - you say she has been in heat before and each heat increases the chance of mammary cancer later.