I was on my back for the delivery, but when I think about it now I was most comfortable when sitting on the toilet
Being on your back can give you as much as 20-22% LESS room inside your pelvis for a baby coming through cmpared to squatting and hands and knees positions - that's alot when you think about it, several centimetres tighter.

You being most comfortable on the loo is a great sign - it means you already know one of the positions your body likes to birth in and can ask for a birthing stool for next time.

they tried moving my postition. I ended up with midwives and DH holding my legs up near my head.
One of the most effective ways to free a dytocia and yet one which seems underused, is the Gaskin manoeuvre, named after the midwife Ina May Gaskin, though she learned it from some indigenous people somewhere. She reports 100% success with it and no baby injuries (some women tore a little). If a dytocia occurs the mother is helped to turn onto her hands and knees. The combination of movement to get there and the opening of the pelvis hands and knees brings unsticks the baby.

The use of traction on the head to free the following shoulder does risk injuries as you describe (though full recovery is both possible and common, even if it does take a little time ), another method is to break the collarbone of the stuck arm to narrow the shoulders. Most Obs go for the first method because it *might* result in injury whereas the second obviously will.

I too, in the pain, needed a crowbar to get me to move, but next time i'm going to make myself a sign that says "MOVE!" and put it right where i can see it!

There was probably a positional factor too, so your baby was coming at a slightly bad angle perhaps, Spinning Babies website has masses of information on Optimal Foetal Positioning and New Active Birth and most things Sheila Kitzinger has written can tell you more about the "birth dance" - moves you can do and positions you can assume which will keep you comfortable and open your pelvis to let baby down and through and out into your waiting arms.

If you'd told me you were delivering on hands and knees, the obs had you crawl and deep-squat and when all that didn't work the lodged collar bone was broken AND the head traction/turning used, i'd be more cautious about saying this, but given the situation you describe i honestly cannot see a SINGLE reason why you should expect a dystocia in ANY subsequent deliveries. Besides which (probably because the experience is traumatic and leaves people asking questions which give the answers they need to have an easier time with the next birth) like Kelly, i have never heard of anyone having 2 dytocias. You sound like you already know alot more about it all than you did last time. Knowledge is power.

Bx