Repair ANY problems with the car, then work on suspension and then get something better than open diff, maybe rock with vlsd or welded for awhile until you can get LSD. Pretty much what Rob said.

You're not cool if you take the corners like a boat on water.
16 year old stock struts & springs scares me.

But above all, sounds like you don't have much $$$ to play this sport, so my suggestion is FIND A BETTER JOB!!! but stay in school. Ask mom & pop to hand over some money if it helps.
Remember, drifting should be a recreation, NOT a career.