Hi JJ - sorry for late response, only just now seeing your post.
Crampy, regular contractions can be ptl but can also be bh due to uterine stretching. I had exactly that from 20wks with the twins and around 24 to 30wks they came regularly every day for a few hours and were sometimes as frequent as 3/4 times in an hour.
It is tough to call, but the general rule is that if they are more frequent than every 10mins it is more likely ptl. It is very dismissive to say they are bh due to the poly without carrying out further checks. If this were the beginnings of labour then they could administer steroid shots at the very least, even if labour couldnt be stopped. The problem with it being a weekend is that you have skeleton staff who are frequently dismissive and not familiar with each individual case.
My advice in a nutshell would be to shout louder honey. With your complicated history they should be taking every cramp, twinge and tightening seriously. It is still quite feasible that you are experiencing bh due to your size (remember that I and other twin ladies experienced lots of tightenings which very closely mimicked the real thing, but did nothing cervix-wise) but it's also possible that you're experiencing the beginnings of labour.
My bh were exactly as you described, a radiating ache in my lower back which moved around tot the front and left my bump tight. The low down kicks and bubbles are not labour related, and more likely baby kicking your bladder/cervix - harmless in itself. I doubt your stitch is giving way either, it won't open now unless you began to have full on contractions. Even then it would stay put and your cervix would dilate through it - you would definitely know you were in labour tho before that happened.
The Consultant is correct that you would have bleeding and/or broken waters if you were in established labour, but the point here is you could be in early labour before any of that happened and something could be done to help before things progressed.
Sorry if this isn't much help. It's so hard to call JJ. If the cramps subside again and don't persist, then it's more likely you're experiencing bh. these too could cause some brown spotting as old blood is dislodged in the process. Either way, your pregnany is complicated and you need to be heard hun. Don't be dismissed lovely. When they monitored tour contractions and found them to be 10mins apart, did they offer some kind of management plan for you?
Will be thinking of you tonight. Will actually PM you my mobile number and if you need to ask something urgent then get in touch, even if you can only manage a text. Take care xxx
feel better soon Christiana 
