Switching job in Malaysia -Cancellation and Apply New

Friends,

I am currently serving notice period with my current employer and few days only left. Mistake i did (1) Without offer in hand, I resigned due to internal politics (2) attended and cleared all 3 rounds of interview in a new company and not told that i am serving notice period upto end of this month.

Problem now is, new employer haven't released the offer letter yet, they are dragging and asking me for another round of technical interview and i have only few days of notice period left with my current employer, even though my visa expires 2017 with current employer they will cancel after my last working day right

Suggestions welcome to handle this situation, How to make my current employer to wait for a week of time after my last working day and How to tell my new employer that my last working day is in few days? wont it create bad impression on me?