my current income is over poverty line but last two years are little low . do i neend co sponsor.Thanks.

I think this thread will help you answer your questions.

http://www.visajourney.com/forums/index.php?showtopic=116393

Is it 100% or 125% of the poverty line. Current income needs to be at or over 125%.

If is a bot short, you can use assets like bank accounts. Assets are worth 1/3 income, so if income falls below the line by 1000, then 3000 in assets are needed.

Income requirement is Gross income before tax and deductions. NOT take home.

If your income exceeds 125% when counting self, any dependents, and the immigrant, then you should be fine.

I think you do not need a co-sponsor. I was in a similar situation, we went through K1 & AOS without any problems.