I've never heard of a chiropractor claiming to be able to treat infertility, although I believe they are more regulated here than they are in the US. And honestly, it's extremely unlikely to be legit.
I'm saying this as someone with scientific training and who goes to a chiro regularly for back/neck issues, chiropractic treatment has absolutely nothing to do with the reproductive system. Its just not scientifically plausible that it could improve fertility.
My personal opinion is to stay totally away from any chiro who claims to be able to treat anything other than spinal/skeletal problems or issues that can be directly related to nerve problems from the spine. In my experience any chiro who says they can treat other illnesses (unless they are also a registered naturopath or similar, and even then I'd be careful) is a quack.
I hope this doesn't upset you, but I hate to see people get taken advantage of. You've obviously had some treatments already, if they haven't done the trick so far, then IVF is probably your best bet.