Where am I missing?

Folks,

I am in cross-roads of my preparation.I will greatly appreciate if you can assist me.

I have been spending 20-23hrs a week on GMAT preparation and my test scores(ETS) are still in the category of 520-550.This has been frustrating based on the time and energy that I spend on GMAT.Thus I have have embarked on "Where I am missing strategy":-)I have used the postings on GMATCLUB forum as a basis for this effort.I would greatly appreciate if you can help me to discover my areas of weakness+recommend strategies to address them.Please bear with me,this posting is a long one.

As a non-native English speaker, Verbal is my challenge.As for Quantitative I have been making many careless mistakes and do not have a through understanding of the concepts.My analysis for "What I have been doing?":
a)I have been studying for GMAT by viewing the Presentations off GMAXONLINE(https://www.gmaxonline.com) + reading Kaplan for strategies.
b)I regularly do the homework(OG problems) after viewing each presentation.My homework scores are as the following:
Quantitative:
1)Numbers:
++++++++
P.S.:26/40==> 65%
D.S.:15/19==> 76%
Average Time taken: 3 mins

2)Fractions:
+++++++++
P.S.:21/20==>70%
D.S.:7/11==>43%
Average Time taken: 3mins

3)Percents:
++++++++
P.S.:40/50==>80%
D.S.:15/19==>79%
Average Time taken: 3mins

4)Algebra:
++++++++
P.S.:16/19==>84%
D.S.9/10==>90%
Average Time taken: 2mins

5)Geometry:
++++++++
P.S.: 27/33==>82%
D.S.:13/17==>76%
Average Time taken: 3m30s

6)Averages:
+++++++++
P.S.: 11/13==>84.6%
D.S.: 4/6==>67%
Average Time taken: 1m42secs

7)Consectives:
+++++++++++
P.S.: 3/3 ==> 100%
Average Time taken: 2mins

8)Median/Mean:
++++++++++++
P.S.:6/8==>75%
D.S.:2/2==>100%
Average Time taken: 2m 30secs

9)Standard Deviation
+++++++++++++++
P.S.2/3==>67%
Average Time taken: 2mins
+++++
I have yet to drill on the following:
i)Exact areas of weakness in each of the above sections.
ii)Why I overshoot 2mins timeline for each problem 9/10times.But from what I see if I understand the concept throughly I can meet the timeline.

Based on the above scores,you can see that I am in the 79%(217/273) category grossing @ an average of 2mins 45secs.I will addressing (i) + what kind of careless mistakes I make in each section.But I do not have an idea on how to improve my time per question.Please let me know your thoughts on this.In addition please let me know other areas that I need to address too.

As for Verbal:
Sentence Construction:
+++++++++++++++++
1)Subject Verb Agreement:8/11= 73%
Average Time Taken:2min 15secs
2)Subject Verb Agreement + Pronoun: 13/22 =59%
Average Time Taken:2min 30secs
3)Parallel Contruction:31/48=62.5%
Average Time Taken:2mins 17secs
4)Problem with Modifiers:12/16=75%
Average Time Taken:2mins
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Based on the above we can see:
Total Score: 66/97==>68%
Average Time Taken: 2mins 15secs.

I have yet to identify the pattern of mistakes that I make in the above section.
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Critcal Reasoning
+++++++++++++
1)Finding Conclusion: 7/10 = 70%
Average Time Taken:3 minutes
2)Assumption:7/10=70%
Average Time Taken:2mins 39secs
3)Strengthening/Weakening Reason:33/48 = 74.2%
Average Time Taken: 2mins
4) Finding Inference:1/4 = 25%
Average Time Taken: 2mins
~~~~~~~~~~~~~~~~
Based on the above
Average Score:48/72 = 66.67%
Average Time: 2mins 15secs

Like Sentence Construction,I will be identifying the pattern of mistakes that I make in the above section too.
~~~~~~~~~~~~~~~~
Reading Comprehension:
1st Passage(Q1-6):Scientific: 2/6
2nd Passage(Q7-12):Archaelogy: 3/6
3rd Passage(Q13-18): Business: 4/6
4th Passage(Q19-24): Management: 3/6 [Attempted:4,Mistake:1 and Did not attempt:2]
5th Passage(Q25-30):Science:0/6
6th Passage(Q31-36):African American <and> Migration: 5/6
7th Passage(Q37-43): Economy <and> Children:3/6[Did not attempt:1]
+++++
Based on the above:
Average Score:20/42 ==> 45%
Average Time per passage:15mins <Not accurate>

I have discovered that I get lost in 2 kinds of passages:
Scientific and Political.
Thus I have started reading Scientific American and Editorial of NYtimes on a daily basis.
I usually select a passage with 55 lines and time myself on how long I spend on reading the passages.Inadverdently,I spend about 3mins 20secs on an average.This is inclusive of the time that I take to write a line about each paragraph of the passage.

I have been doing this for the last week and I need to start attempting Reading Comprehension Passages in OG.
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A commonality b/w Verbal and Quantititative is the amount of time that I spend on the questions.This is usually more than the allocated amount.I am really not sure on how to address this piece.Please let me know your thoughts.Tx.

Anna