At 17 weeks some cramping can be normal as your uterus is growing and stretching, but that pressing sensation on your bladder is likely just the weight of your growing baby putting pressure there, which happens to many of us around this stage. That said, it's still worth checking with your doctor or polyclinic just to be sure everything is fine, especially if the cramps feel sharp or you have any bleeding or other symptoms that worry you. They'll be able to give you peace of mind and rule out anything else going on.