I think most women here will reply that anytime we had a lot of BH contractions, it meant to DRINK MORE WATER and SLOW DOWN. I don't know about diagnosing a uterus as irritable - seems silly to me, b/c your uterus is doing a lot of work and stretching during a twin pregnancy.
My BH contrax started around 26 weeks. I quit work soon thereafter. Anytime I had a lot of BH contrax in a row, I would chug at least 4 glasses of water and lay down, continuing to drink water. Sometimes I took a relaxing bath and drank a bit of wine. By managing my activity and stress levels and ensuring that I was really well hydrated, BH contrax never became an issue for me. Actually, in the end I was trying natural induction methods and birthed at 42 weeks
I did talk to an OB about my BH contrax. Like you, my cervix was long and closed. However, the OB was quick to prescribe me anti-contracting medication; I researched the meds when I got home, found some scary stuff about the medication, and realized that there was no way I was going to take it unless to prevent a real emergency. I never touched the pills. In the end, my BH contrax were what I think is 'normal' for a twin pregnancy. Also, realize that BH contrax can be a good sign - your uterus is doing a bit of exercise to tone itself to help push out two babies in several months.
Take care of yourself, mama!