Is my cat pregnant?

I'm new to this.. I'm wondering if my cat is pregnant. I caught her and my male cat together about 3-4 weeks ago when she was in heat. She doesn't look like she is getting bigger she's been very affectionate this week where usually she wants to be left alone and only pet when she wants it.

Yes, she is likely pregnant.

In my experience, they will only start really showing in the 5/6th weeks. Its hard to tell in the picture, but are her nipples tinted a little pink?

To me they are a light white - ish pink. Her nipples have popped out more than what they were a couple weeks ago they aren't hard or anything. This week my male cat has been snuggling up with her all day and night. She never let's either of my other two cats cuddle with her.

when my cat was 3 weeks it was definitely hard to discern whether or not she was but if you give it time, her nipples will become more apparent, as they become bigger and also more of a pink color. Taking her to the vet to check is also another option

I'm going to wait a couple more weeks to see and fingers crossed she is because I want kittens!

You should consider having your male spayed now. It takes up to a month for males to be sterile after their surgery, and females can get pregnant again within a week of delivering.