Stomach pressure?

Hi guys, I'm 20 weeks and this is my first pregnancy. I don't know much about it, and just wanted to see if this was happening with anyone else, or if anyone knows what it is.... Well anyways about two weeks ago I started feeling as if the baby was pushing out on my lower stomach... A couple times a day my lower belly will get really hard and I can feel pressure. It's not painful. I haven't felt any obvious kicks yet but many of this tummy pressure. Is it actually the baby laying in an odd position? I've read a lot about feeling the baby kick, but nothing really on feeling th entire babies weight lol. I'm going to ask my doc my next appointment, just wanted an earlier opinion! Thanks:)