You might have a fibroid. Have you had an ultrasound recently?
It could be a fibroid especially if you also have heavy bleeding during your period. Another possibility is a simple hormonal imbalance. Producing too much progesterone, for example, causes this. Not uncommon. I'd see your ob/gyn who can do some blood work to check your levels and an exam to look for fibroids if they are present. Can you see the doctor for this?
Oh my gosh! lol. You are pregnant. Well, that's hopefully good news and exciting. How do you feel about this??!! I this a welcome event in your life? We have pregnancy forums here that I'm on and hope you look us up! https://www.medhelp.org/forums/Pregnancy/show/152