Like you, I left college early for a job. At first it seemed like a really good idea. I was flat broke, my grades were only so-so and, quite frankly, I wasn't exactly sure why I was even there. It wasn't until about 5 years down the road that I ran into a few brick walls.
To try and overcome these I made some tweaks to my resume. I still listed the University I attended however I left out the dates. I also left off what I was majoring in.
If I was asked a direct question such as "What did you get your degree in?" I'd be completely truthful that I did not get a degree but majored in X while steering the conversation to my experience. That said, at the time almost no one asked. Today I run my own company so it's really not an issue.
How big a problem is being a dropout?
Simply put not having a degree, any degree really, closed a LOT of doors to me. Larger companies demand that you have some kind of degree, even if it's in Underwater Basket Weaving just to get an interview unless you happen to know people. This basically means you are going to have to up your social skills and keep good contacts.
Funny story - a friend of mine got a job as a DBA. They had no previous computer experience but they did have a degree in English Lit. The company just needed to fill a spot and a degree was required..
That said, there are numerous companies that normally don't care. Startups, small businesses, etc. These are more likely to grant an interview based on your past work than to use a degree to filter people out.... unless the industry you are in is has a plethora of candidates.
Which is the real kicker. Professions can go through spurts where there are not enough "qualified" people. In those cases it's far easier to get in somewhere without that piece of paper. However they tend to pay very well and, as such, will attract more and more talent. Meaning at some point market saturation is reached and companies then move from hiring anyone they can to being able to filter out candidates because of various things like no degree, the font used on the resume is "awful", they wore the wrong tie to the interview or whatever.
Speaking of which - @JoelEtherton is absolutely right - gone are the days that you can get a decent job in IT without a degree.
My point is, if possible, go back to school now. Lots of people work their way through college; I suspect you just need to set it as the priority. It may seem like a good idea to do your own thing now and not be saddled by having to attend classes. The reality is, if you get the degree now you'll have a MUCH easier time later forging your own path instead of having so many doors closed that you'll hit a hard ceiling.