R0713,
I think all serious GMAT students have been in the same predicament. And you are right, most of us work full time, have obligations, and find the time to volunteer, work on our applications and visit the schools.
As for me, I started out by first getting all the books I needed and started reading them. I then solved some OG11, and while I did alright, I wanted to do much better. I then got burnt out. I stopped, procrastinated, and whined. I was working 12-13 hours a day at work, plus an hour commute. My job is extremely mentally straining, so the last thing I wanted to do was solve more quant problems when I went back home.
This is what I did to turn things around:
1) I made flash cards for EVERYTHING - 5 Quant subjects, and 2 Verbal. In total I have close to 300 flash cards. They are divided into sections, so I only go through the batch I need to work on.
2) For Quant, I started doing timed batches of 25 Problem Solving questions, and 15 Data Sufficiency.
3) I printed tutorials from various internet sources on quant subjects, like combinations and permutations, etc.
4) I started waking up at 5 AM to solve questions, and then revise, read, understand, make more flash cards at night. My brain works best in the morning, and at night its just for reading and revising my morning work.
5) I use GMAT Club everyday, especially the Math Quant forum. I read the discussions on posted Quant questions.
6) And finally, stay positive and eat well.
Hope this helps. Don't give up!