Un4Seen:
Could you please suggest some other MOSFET instead of NDP6020P-ND? These are barely found and expensive on eBay and cannot be found at all in my town's local shops...
You'll probably not find a suitable P-channel mosfet in your local shops. I suggest you order them from one of the major component distributors. If you are prepared to use a mosfet in an SMD package, then the prices are much better, for example this one http://uk.farnell.com/taiwan-semiconductor/tsm2311cx/mosfet-p-ch-20v-4a-sot23/dp/1864586.