Late Pregnancy Symptoms

Hello everyone- hope you are all well!... Question... This is my 3rd child and I am 40 yo. I have a 10 yo daughter born at 38 weeks and a 6 yo son born at 37 weeks. Today I am 37 weeks with my second daughter. At my 36 week OB/Gyn appt, I was checked and told that I am 50% effaced and almost 2cm dilated (the week prior I was completely closed). The baby has been head down for weeks now... I've had a variety of symptoms and signs of impending labor... The baby has dropped a bit and was told that once she fully engages, my labor will go quick so I need to be prepared... The symptoms bothering me the most are fairly severe nausea coming on randomly accompanied by an upset stomach. I also get pretty bad heartburn and feel the need to go to the bathroom MUCH more than usual (#2- sorry... gross)... but when I try to go, there's barely anything resulting and it has not been loose... With my two other children, I didn't experience the severe nausea and upset stomach symptoms... I don't sleep well at night lately and I have to sit up most nights due to my tummy and heartburn. The baby is pretty active and moves a lot too!... Anyone else have these symptoms? Were you close to labor when you started to experience them? This has been going on for about 2+ weeks...