Stuck: any advice, tips and tricks

Hello dear GMATers,

Even though I have been preparing for GMAT since February 2018 (with huge breaks of 2-3 months), I started to use all the benefits of GMAT Club recently. I really love this platform. I truly learnt a lot and still I am. Thanks to the developers and all members!

The reason why I am writing this post is I am stuck
The university I am applying for requires to have GMAT score of 600 and more ( 650- I set a goal for myself). It seems like it shouldn't be a huge problem to get 600, right? Unfortunately, not in my case.

Could you have any advice, tips & tricks etc? I would highly appreciate them!

My current GMAT situation:
1. I tend to study every day despite having a full time job. Every day I need to solve at least 5 CR, 5 SC, 5 math questions and 2 RC texts.

2. According to GMAT Official Tests I got following scores:
- GMAT Practice test 1 : 480 Q43 V22 (did reset)
- GMAT Practice test 2 : 440 Q16 V30 (did reset)
- GMAT Practice test 3 : 340 Q10 V9 (did for the first time)
- GMAT Practice test 4 : 500 Q28 V40 (did for the first time)

3. After a really huge break, I have been preparing for GMAT since the beginning of August of this year.

4. I did couple of CAT's tests both verbal and quant, there I got very low scores. Verbal (32 and 6), quant (8 and 17). Are CAT's tests harder than GMAT Official Tests? I felt like they are.

5. For math I practise sub-500 questions. For verbal I practice both sub-500 and 600 level questions.

6. I would say that verbal is a bit stronger than quant, but still as soon as I get a harder question I fail to answer it correctly. Could it be reason why I am successful with 600 and 700 questions?

7. I would like to do GMAT before New Year. Do you this is feasible?

Thanks you in advance and I'm looking forward to receiving your comments!

Best wishes,
Agnes