How about just offering it for sale on envato under their licensing. Yes, you give up a bit of revenue because they take a cut but you don't have to pay a lawyer to draft a license for you, and you can still offer it on your own page under your own non-professionally-drafted license at the same time if you really want to do that too.
On another note, I personally see a license as one of many signs of product maturity. If there is a well established license in place, then that tells me the product is likely pretty stable and this along with other factors helps me determine if I should make the time investment to try and use that product. I think the issue here isn't whether your current users are having any problems with your license, but rather there are likely potential users who haven't even touched it because of the license. Having an explicit license is very helpful in the long run.