This is exactly why it's best to start off by following a well-designed program. If you keep trying to make it up on your own, you run the very-likely risk of even more months and months of little progress.
Everyone here works and trains, or goes to school and trains, or goes to school then goes to work and trains. Your schedule and priorities are whatever you make them. You definitely don't need to workout 7, 6, or even 5 days a week, but unless you're working 40+ hours outside of school, I don't think it's a major issue.
There's a decent free substitution for most exercises. But the sooner you can invest in a gym membership, or a squat rack and/or cable pulldown for your home gym (some are pretty inexpensive), the better.
If you're 6'4", there's no way you can safely use a flat bench as a squat rack, unless you've got some very weird looking bench setup.
Dial down the attitude, boss. Nobody said you can't see how your body responds during a pre-designed program. And like I said, you've already done the trial and error-thing for a few months and you ended up with no muscle. Keeping an open mind will let you get the most results by following a program for 8-16 weeks, track your progress along the way, and make an informed decision about what to do afterwards.
Look into any of these:
(^ Click "Oldest First" to read it properly)
Also, as a taller dude, you'll need to eat plenty to fill out. Don't underestimate the importance of eating at least 3 meals a day, every single day - basic stuff like whole eggs, red meat, chicken, tuna, milk, bread, potatoes, rice, oatmeal, fruit, vegetables, peanut butter, etc. Don't eat like a pre-contest bodybuilder, eat like a growing young guy.