Back Pain-please advise!

Ho
I am 7w2d pregnant with my first baby. I have next to no symptoms. I have been to the doctor and saw my bean and his/her heartbeat 5 days ago. I have another appointment in 8 days. 
I have considerable back pain. I've had it for about a week, and before that on and off. It's not sharp and it isn't constant, and it doesn't keep me up at night. It's basically a dull ache in my middle back.
I am kind of constipated (sorry, tmi), I am definitely not drinking enough water (yet), and I'm a teacher, so I'm on my feet all day. In addition, I've stopped working out due to my pregnancy anxiety, which is through the roof, and I am definitely sleeping differently than I normally do, because I'm trying to stay on my left side (I'm usually a stomach or right side sleeper).
Do you think these factors, plus the regular pregnancy pains, could be causing or contributing to my back pain? Or is this something to be worried about that I should call my doctor? Is it possible that this is just backpain and not something terrible? 
Like I said, this is my first pregnancy and my husband is the only person who knows, so I can't talk to anyone except you ladies, so any help is appreciated.