Well if that's the case, maybe switch drs. My sister had her cervical cancer grow back 3 times and the drs were still hesitant until she assured them she has 2 kids, no more (she was 26). Maybe you can convince them if this is what you're wanting.
I've had a D & C and a laparscopy. I've had the Merina in but it stopped my period all together and the pains were worse. I can't convince him to ge snipped (losing his manhood as he says :/). My son is 7 and my daughter is almost 2. I was one two other BC's when I got pregnant with them. Trust me when I say I do not want anymore children. We are already busting our butts barely making it to survive, I am not putting another child in that situation. Plus, we have always agreed that IF we ever want another child, there are plenty of children being put up for adoption here in the US that nobody wants. (That is of course we finally get stable enough to do that) I am planning on seeing my doctor if I ever slow down in bleeding long enough. My doctor will most likely refuse, to be honest, because he STRONGLY against removing anything. I also forgot to mention that I also have HPV. So, I do have my yearly paps and everything. I know I'm slowly running out options to stop the bleeding.
Honestly your dr will resist if you ask for a partial hysterectomy -for the reasons kitkat suggested: you're only 28, what if you want more kids, and lets try something less permanent before.
Personally I think you should only get this if nothing else is working. I don't know how many birth controls you've tried, but obviously the one you're isn't for you (and can be considered dangerous if you're getting light headed from blood loss). Partial hysterectomies are very common, but keep in mind they are surgery-something not to enter lightly. So right now, if you haven't tried many other options, see what other options you have. If you've exhausted your options thought and you're facing surgery one way or another (to remove whatever is built up), perhaps you should just get it out.
What about trying another form of birth control instead and seeing if that helps? Obviously a partial hysterectomy is an option that could work, but it's just pretty permanent though. It's good that you and your partner have discussed it and decided you didn't want any more kids, but then you don't know how you might feel in a few years since you're only 28.
I would speak to your doctor about all your options. Is there not a surgery you can have that just gets rid of everything that's built up? Can't remember the name of it now but I know that it can provide relief for those suffering from it. Definitely something to discuss with your doctor though.