Holy smokes! That sounds awful! My idea of bad period cramps are a minor irritation at worst. Your description of period pains sound like my labour pains. The optimist in me hopes that there must be a cap on how bad pain can get... isn't there? D:

IMO, I'd say go ahead and give the homebirth a shot anyway, if it's something that you want! Especially if you live within a relatively close distance to a hospital and you have midwives attending. I"d let her know about the pain issue though, she may have some insights as to how things will go... First labours are generally so long that if you find the pain too much to bear then you have plenty of time to go and get all nice and drugged up. Epidurals often make it so that you can't even feel much of anything at all. Plus you may find the pain more bearable because labour has such a big reward at the end... While periods are all pain and no reward.

Whatever happens, good luck, and congrats!