GMAT Strategy

My exam date is 22nd October, which is 17 days from now. I know i am way too behind my schedule and i had expected to complete OG'13, Kaplan premier, Manhattan strategy guides by now. But i have managed to complete only the manhattan strategy guides(4th edition) and the corresponding quants questions from OG'12. I have completed Manhattan SC. Still i am facing problem with SC. From OG'13 I did starting 40 questions, getting around 8 right out of 10. After that from question 40-70 i have got 5 right out of 10. and this has become constant. if i do 10 questions i HAVE to get 5 wrong. dnt know how to proceed now with SC. CR i did from powerscore, it improved my CR a lot. RC i am following strategy from Ron's video. DS is currently my weakest topic. I have to practise more.

My scores:
1.Manhattan CAT 1: 470 (without any study)
2.Manhattan CAT 2: 500 (studied but very less)
3.Kaplan CAT 1: 570 (i had studied this time, though did bad in rc and cr)

Please suggest me what should i do to improve in SC and DS and do you think there is a scope of somewhat improvement by 22nd October..
Also, my judging based on that i am doing 5/10 right and 8/10 right. is it correct? or should i maintain the error logs and treat every question differently. Please help..