I would be inclined to trudge forwards b/c you only have three more semesters to go. If you can get grants for next year, then I'd certainly keep going. Unless I was drowning in debt, I'd probably keep going with loans as well.
If you do take a break, would it be easy to get back into the program? Often, once a person is out of school for a while, it can be hard to get back into the school mode and people sometimes don't go back. Not everyone is like that, of course, but it may sometimes be best just to trudge forward. From what you said, it sounds like you are not one of those people b/c you know what you want and you know what you need to get there, but it is a possibility. Are you able to take on an evening job a couple night per week or a job on the weekend to help offset the cost?
I recently changed my username, but I still say "Hello" to all those who know me in real life! Hi P, S, T and K!