I Am 12 Weeks Pregnant, Age 43, 5th Pregnancy. For

I am 12 weeks pregnant, age 43, 5th pregnancy. For most of this pregnancy (since week 4 or 5), I have experienced uterine contractions, more so when I sit or lay down (i.e. at night) than when I'm active. They've slightly morphed or combined with what now feels similar to menstrual cramps. Within the last week, I started passing thick yellow mucus. Not the clear or white running mucus you normally have, but thick yellow mucus with a more "snot" like texture. I'm concerned this is my mucus plug and the contractions that I'm having is a sign of miscarriage or preterm labor. When I've mentioned them before to my doctor or nurse, they dismiss them as normal. Are these symptoms normal?