I'm a big proponent of the idea that if you can do the work and have demonstrated success, your level of formal training, degrees, and certifications doesn't matter.
There are two big questions you should strive to answer positively for any perspective employer. Can you do the work? Can you be successful building functional UX?
How you go about proving this is different for different people, and formal training usually seeks to answer the first question rather than the latter.
In all honesty, I never had the time or money for formal training once I moved on from my college days. For quite some time, web development and my understanding of usability was a mere side business as I worked on my journalism career. When I started to think about getting into the field, I knew had to answer the "I can do the work" side of the equation a different way.
Fortunately, my previous job incorporated quite a bit of UX work, though my job title wasn't anywhere near UX-related. I also volunteered my services for open source projects, and worked with a few independent developers on smaller projects to hone and prove my skills. By doing this, I was able to build a portfolio of real-world experience that was enough to convince my current employer that I satisfied the "I can be successful at UX" side of the equation.
It sounds like you have a similar situation in that you have experience you can emphasize and build on to prove that you can actually do the work. The next step is to prove that you can successfully apply that knowledge to real-life UX issues. If you have a portfolio of work that allows you to speak intelligently about your UX contributions to a project, then you have a great start. If not, you'd see a benefit of going through formal training that allowed you to build a problem-solving portfolio of work based off your school assignments.
Additionally, employers in general value real-world experience over classroom experience. If you need to go through formal training to build your skills and portfolio, you'll want to make certain that you can speak extremely well to how your projects would translate into real-world success. The best way to do that is to get a mentor and discuss your classwork as you go, with a focus on how your mentor applied similar knowledge to real-life UX, what worked, what didn't, and why.
I hope that helps and makes some sense. Let me know if I can clarify anything.