Bullshit. I don't know what you are leaving out of this equation, but, ignoring the schedule conflicts of working full time and going to school full-time, an $8/hr job paying just FICA will net about $15k assuming ZERO income tax. Minimal rent (as in A ROOM) is about $6k/yr, FOOD STAMPS for one person are about $3k per year. Right there, you've got a whopping $500/month left For EVERYTHING else: transport, utilities, insurance, clothes, household supplies etc. Even most state schools ring in at about $9k/yr just in tuition, so you're already in the hole $2k and you haven't bought a single book or so much as washed a sock.
Unless you're riding on a pile of grant money or have free housing, food etc. ("without a penny from my parents" is a lie if they're housing and feeding you) -- your scenario just doesn't stand up to basic arithmetic.
Of course, then there's the obvious problem of attending 15-18 hours of classes scattered between 8am and 7pm M-F and somehow still finding the same contiguous 8-hr per day slot in which to fit "work" and to maintain your 4.0, at least another 30 hours for "study."
In short, you are full of shit. Either you made a LOT more than $8/hr, at a magical job with no set schedule to boot, paid NOTHING for housing and food, and/or were heavily subsidized by other means public or private, or you're just flatly lying.