How little sleep can I get and still function this month ?

Graduate my technical college program in mid may and this is what I still need to do. 96 hours unpaid clinical at a hospital pharmacy (starting today), p with C or better in all my 16 credits of cles (some grades have slipped a little so I can't miss anymore in order to p), work at least 25 hours a week at my job as well as extra spontaneous, when needed, work for my dads business, and try to keep the little social life I have. My current schedule is M 12-1 cl and 2-10 clinical with minimum 2 hours of travel. Homework is due for that cl on Monday so I do it before cl normally. TUE class 9-1 and clinical 2-10 plus 2 hours minimum travel. Wed class 9-7 with a 3 hour break in there (mostly used for homework). Thur is class 9-11 and work either 12-8 or 2-10 with 2 hour minimum travel. Friday-Sunday is work (random shift). Problem is that if I try to get 6-8 hours of sleep a night, I don't have time to do all my homework. I want to know is how little sleep will I need to get buy. It's only till graduation that I need to do this, and I do have access to dextroamphetamines and mixed salts (adderall) if needed, but that's a last resort