The obvious answer would be to focus on your dentist career (long term security) and make DJ-ing your weekend job to keep you afloat financially.
A laptop (needed for college anyway) with a dual-boot option (so depending on the way you start it up you have either a college laptop or one set up for DJ-ing, all in the same hardware) and a decent controller (makes for a great xmas/graduation gift, hint, hint) will give you all you need to practice with (and a monitor speaker, microphone and headphones, but since you’ve been DJ-ing already I am guessing some of it already exist for you). For playing out, just strike a deal with a local rental company (they’ll usually give you 15-25% margin) and just let the customer pay for equipment (if you are not playing in a venue that has gear) and take the margin. No need to go ape and buy that stuff.
IF (big IF) you are ment for music, you’ll figure that out as you get good and booked. If you happen to turn out a second tiesto, afrojack, armin or guetta, there is plenty of time to quit school and go music full time :-).
Greetinx,
Chuck