Is this much pain normal?

I am 24 weeks 3 days pregnant with my first. I'm having horrible lower back pain if I lay on my back for 20 or 30 minutes at a time. When I go to stand up it HURTS! I don't really feel pregnant, except for a bigger belly and bouncing baby, instead I feel like I just turned 90! Ugh! So, is this much pain this early in my back normal? I have a doctor's appointment in 2 weeks, so I will definitely mention it to him on the 28th. Also, not sure if this has anything to do with the pain, but, I'm busty. Started pregnancy in a DD and now I'm almost an E. :[