It really depends on the PERM application and how your lawyer builds the Job requirements however , if you are planning to use only 2 years of experience you might get audited in PERM. I say MIGHT because i have seen a lot of people not having any problems.

The whole point of PERM is to prove that there isn't any gore workers qualified enough for the position. With only 2 years of requirement that might be hard to prove and they might set your employer AUDIT / Supervised recruitment effort.

A lawyer would be the best place to start with this. In fact you will need a good lawyer.
Also the 15 months experience you have in the current company cannot be used if its for the same position. Which means if you were a software engineer for that 15 months , the position they should be applying you CANNOT be software engineer (similar job duties.)

The 2 years of experience requirement should be a pre-requisite for the new job position.

Good luck.