Quoting MrsSinatra:" Idk. This whole pregnancy I have had like no desire. But these last 2 months I have been a horndog. I ... [snip!] ... before bed thar maybe we can try something tomorrow... MAYBE?! ugh... I'm so irritated... its been over a week. smurf. ;("
I know this probably isn't what you want to hear, but i would strongly recommend not having sex if you're having issues with contractions. The orgasm can cause contractions, so can nipple stimulation. Sperm can help your cervix soften and obviously shoving anything up there when it's already irritable is just a bad idea. Not to mention the risks of you getting an infection if you're dilating at all are a big big deal.
Obviously you don't want to take the advice from some random person on the internet, but if it was me, i'd call my OB and see what he says. If he says it's fine, then you can always mention that to your bf.