Apologies for the novel I'm about to write and I just want to say that nobody knows how FAA hiring policies will change except that they will change every year or two. Also, lest I insult someone, I'm assuming your end employment goal is with the FAA based on what you wrote and in no way am I intentionally ignoring a career military or contract tower controller career path
If you really want ATC you probably want to maximize your chances for being hired. Your three options are off the street (OTS), FAA approved college degree (CTI) or the military.
OTS is open to anyone with 3 years of combined full time work/college or a combination of both with allowances to convert part time work to full time ie, 1 year of working 20 hour weeks = 6 months of full time work. OTS openings come and go sometimes with several years between OTS openings. If I'm serious about being a controller I'm not going to depend on OTS. I'll apply on every bid I qualify for, but I'm not going to sit on my hands and make this my one shot at getting the job.
Military. Obviously an excellent route, but not your preferred option and there is nothing wrong with that. Many have said you may have a hard time getting a guaranteed ATC slot. If you enlist open general with a wink saying you'l get ATC, yeah you can get conned. If you know that service's ATC career code and say (Air Force example) "1C1X1 and only 1C1X1 please." and aren't afraid to walk away if the recruiter does anything but what you ask, you'll have an easier time.
One thing to be aware of is in the hiring eyes of the FAA all services are the same, but not all of what a service's controllers might do will be considered "real" atc by the FAA. Army tactical ATC from stage fields and Navy carrier ATC qualifications do not count with FAA HR. Another is, and another poster alluded to it with their son, unless you get all of the ratings in an FAA recognized environment, you don't qualify to apply under a military bid. So if you get flight data, clearance and ground at a tower and get shipped off elsewhere before getting local (tower), what you did there in the eyes of FAA HR means nothing.
The CTI route seems to be the one you want. If I were in your shoes I'd apply today to any and all 2 year CTI programs. Most of your credits will transfer and you'll have a CTI degree in a year or two. You can then transfer those credits back to where you are now and resume your current degree.
As Mark said, no path is a guarantee and I'd strongly advise becoming hire-able ASAP and then continue your life as if ATC doesn't exist. The wait to get hired can be very long and especially frustrating if you just sit out a menial job waiting for the phone to ring day after day.