Hei, don't be discouraged. It's really hard to stay on the steay study regiment. Job, kids and other stuff make it exponentially harder. Believe me. Being in the same boat myself, I totally understand.
I would suggest you take some time off. May be a few weeks. Then make another package of prep materials. The package should at least include:
1. All 8 Manhattan GMAT
2. OG 12
, OG Verbal
, OG Quant
3. 4 GMAT Prep Tests
4. 6 Manhattan Prep Tests (Free wih the books).
5. GMAT Club Tests
Give yourself about two months to study consistently for 2/3 hours on weekdays and 4/5 on weekends.
Your schedule should look like this:
1. Two weeks of thorough review (Manhattan Series) including the end of the chapter questions, online flash cards and the Q Banks. They are neat.
2. Then your first GMAT Prep to guage your improvement.
3. That point on, about 50-60 OG questions (start from the end - hardest to the easiest).
4. Take at least one test a week.
With this prescription, you're bound to get close to 700, not just 550.
Listen, I know it's not your ability that's in question here. It's the amount and quality of time you can devote to your study that's the issue. Our heart and brains are literally split in a number of ways. So, please don't call it quits yet. You haven't been able to give it your best shot. Try one more time and try to do it the right way. Instead of pouring in money into prep classes, you may want to invest in child care - sitters for when you study on the weekdays and weekdays.
Hope this helps. Good luck.