Lots of pressure!

Malarie • 26 years old, Married, Mother of a 7 yr old girl & newborn boy!
I have been experiencing lots of pressure with my pregnancy since about 15 weeks. I am now 19 weeks and the pressure seems to be getting worse to where I'm finding it difficult to walk at times. The pressure is really low in my pelvic area. I told my Dr and she said it was normal cause this is baby #2 and all my insides are weaker etc. I'm just a lil concerned. Anyone else experiencing this?