If you have undergraduate degree and 5 yrs experience then you qualify for EB2 category green card process but you mentioned that you are working on CPT and have over 4 yrs US experience. Since I was student here in US too but I had CPT for only for a year but I am wondering how come you had CPT for 4 yrs. If you work over 1 yrs on CPT then you are out of status as per my understanding. How can you prove without CPT you have over 4 yrs of full time work experience?

However if you have masters degree and your employer is interested to file for your H1 then go for it. After 6 months or a year you can start for your labor process and go further for green card process.

Good luck !!!
I am sorry if it hurts your feeling with my answer.