Condoms slipping off, although they are too small.

When me and my significant other have sex, the condoms are always way too tight to get on, my penis is 6inch x 6inch, so i'm quite wide. Now it's incredibly difficult to get condoms on, and I HAVE to use lube to do so, there's no issue with this other than because I produce so much pre-cum, although the condom is so tight if begins to SLIP OFF. I have no idea what to do, because any smaller in width would cut off blood supply, and any wider in width may still have the same issue, but without a struggle getting it on. I'm not sure what's wrong, any help appreciated. Cheers guys!