Hi,
I've got 570 and I've taken the gmat a second time to be disappointed again

I've realized that it's important to take some time to master the basic concepts. Before you try to find the answer to some complicated problems, you should check one by one all the basic concepts (powers, ratios, percentage, ...) because you will certainly have to solve problems like this before reaching any probabilities question. after I've taken 2 Gmat tests I decided to wait for 6 month and to take my time to understand clearly all the concepts, doing 1-2h daily for 6 month and taking time to solve the problem.
1st : solve the problem
2nd : solve the the problem with time limit
3rd : solve the the problem with time limit without looking the answers (no picking numbers strategy and no lucky choices), it will help you to realize if you're good or not, but during the exam you can clearly use this technic, just learn how to do without it
I've seen that you've got a 47 in Quants in one Gmat so you should just take some time to work on it and try to keep this level...your problem is clearly in verbal, 6 in Verbal at a Gmat is very surprising but it doesn't mean you can not improve it.
According to your profile, I advise you to study very hard the quant section and then try to improve as much as possible the verbal one but first be sure you can not score below 45 in Quant...and if you can do something good in Verbal it's done...I think it's much harder to improve verbal skills than quant skills so it would be my strategy if I were you
I would add that when you say that you don't understand why you score so low after 3 months of practice : I don't think 3 months is so long, some people take a year to study all the concepts and some can just spend 2 weeks before reaching 700...take time and always check yourself, visit this website everyday and try to answer every new question within 2 mn and see if you can do it...that's a good test in my mind.