Pregnant could this be that I am pregnant with twins or just going to be really big with just one?

It probably means your stomach was really big before you got pregnant, or you are overweight, one or the other.

Tick

I wasn't even big when I got pregnant I am pretty low weight my fiancé said that I had a baby bump and then I noticed it also like I said it looks like I am 4-5 months already

Four weeks should not even be enough to be noticed. Sounds like other issues to size,

You need to ask your ob/gyn if there is something wrong if you look pregnant at four weeks. That is not normal at all. Most women barely show at 3 months pregnant. Make sure your body is functioning the right way.

The only possibility is that you are very bloated and have water retention. Maybe they can do an early abdomenal ultrasound.

Is this your first baby? With the later ones, your stomach will not be as tight.

POSSIBLE pregnancy?

You're not sure? You haven't tested?

GET TO THE DOCTOR! There could be any number of things VERY wrong with that much growth in so little time.