Extra fluid

So I am currently 29 weeks pregnant with my 3rd baby. I went to the doctor this week and my doctor said I gained 17lbs in 2 weeks from my last appointment. He said he’s not too worried considering I don’t have high blood pressure or any swelling. When I went for an ultrasound the tech said I had a lot of amniotic fluid and that my baby is swimming in it. I feel like I am winded a lot of the time or as if I’m not getting enough air. Could this be the issue? And I hope my baby doesn’t come early if that’s a possibility