Braxton hicks or contractions?

So for the passed couple of days I have been having what I believe is Braxton hicks. I have had really light ones until recently, an these ones are quite heavy.... It feels like Charlie horse in my upper stomach. I only get them when siting on the toilet or sitting up really straight!! I'm getting anxious as I've had preterm labor befor an I'm taking progesterone shots. Baby is 32+5 today, but three days ago was measuring 3 weeks ahead (so he would be measuring close to 37 weeks now) in really worried and I don't want a Christmas baby :( is there anything I can do about contractions in the bathroom?