Pressure, pressure, and more pressure

I've been having contractions in and off for a couple weeks now... Start in my back and slide around my sides and into my groin/lower stomach.
When I have them, I get an intense pressure in my vagina, and sometimes it's so bad I literally feel like I'm going to piss myself, then the contraction lets up and it goes away. Other times, it's more like something is just pushing down really hard on my cervix.
Is this normal? Is the kind of pressure you're feeling?