I fractured my coxyx 6 months ago... I also suffer from IBS anyone with back bowel or lower back issues will mostly feel a lot of pressure... swimming really helps and it strengthens all the lower muscles to calm the pressure. I've been doing it 3 weeks now and already feeling a difference. Imagine all them muscles relaxing as your body grows with baby... it causes all sorts of havoc on your whole body x
I always felt a ton of pressure with my first pregnancy. It was extremely uncomfortable. Definitely call your Dr it make sure they don't have any concerns as every pregnancy is different. My son was a preterm labor :( they said the pressure didn't effect that though
This is my second pregnancy and I'm sixteen weeks but I feel the exact same pressure. When I too to the bathroom or sometimes when I just sit down I mentioned it to my doctor and they didn't seem concerned but I'm gonna mention it again at my next appointment