Good to hear from you, and thank you for your service to the United States. I would strongly advise that you pursue your bachelor's degree and take full advantage of your GI bill benefits. If you can do that before seeking full-time employment, you should do so. Having finished my own BS and MA while working full time, it's a load I certainly wish I could have avoided!
If the financials don't work, the key is to put the nose to the grindstone and make sure you are getting at least a few credit hours under your belt every single semester, and at least one of the summer sessions.
My personal opinion is that the field of study matters little. I switched my major to criminal justice as a senior, only so I could take advantage of Federal funding opportunities. Otherwise, I would have been an English major. One of the best police officers I ever hired, Vicki Bourg, had a BA in Restaurant Administration.
I always advise young people to study what interests them, what they would find to be the least tedious. You're more mature, and in your case I would also add this: "What course of study will require the least number of credit hours to complete my degree?"
A Marine with a BA in Synchronized Swimming and some real-world experience still has a mighty strong set of credentials, in my book!
Tom CasadyDirector of Public Safety