Trending @HCL; How much should I ask for my next job?

3+ years of experience, working in HCL (got placed in campus placement). Working as a Technical Lead. My current salary is 10 lpa. Two concerns -

1. Not getting promotion
2. Too much stress as it is a team of just 2 employees, and I am the only 1 working, other team member is my Project Lead as well as my RM

Now, I want to switch, how much should I ask for? I am really confused with this?