Pressure in left hip

I know my baby girl is head down by my left hip, but there is so much pressure in that area that it worries me. I'm almost 18 weeks and have been feeling flutters for a few weeks but I don't know if this pressure is normal. It feels like she's rubbing on or pushing on my hip bone. It's only on the left hip where her head was during yesterday's ultrasound. Should I be feeling this pressure this early?