Ugh I can relate! With my 8 mos old my labor was much like yours. I was 3cm dialated for over a week. I was having contractions like you described and once they started getting more frequent it was 4 days before actual labor started. It was so frustrating! I tried all the tricks, vacuuming, a bumpy car ride, sex, spicy food etc. I think the spicy food may have done it but it also could have been coincidence. I would not recommend nipple stimulation because it can actually cause an unsafe drop in the baby's heart rate, so they do not recommend that unless you are being supervised by a midwife or other healthcare professional.
I know it's frustrating, just try to relax. Maybe take a warm bath or shower, try to get some naps in (because you won't be able to nap much after baby comes lol). Make sure to stay hydrated. You may also want to try to take a little walk. Baby will be here before you know it. Good luck!!!