Green Card Category EB2 or EB3

I need some guidance here.

Background :

After my 12th Science, i did 3 years Diploma in Computer Engineering then i got admission in bachelor in computer engineering second year.

technically Bachelor in computer engineering degree itself is 4 year course, but as i did diploma i got 1 year credit.

My employer start filing my GC process but attorney keep told me your case should go with EB3 not EB2.

(i have mine “education of academic credentials” from Monningside during h1b filing, based on that certificate they clearly mention “has attained the equivalent of a Bachelor of Science degree in Computer Engineering” )

Please guide me is my case go with EB2 or EB3.

Also wanna know wats a processing time till I140 approved in both EB2 or EB3 case.

Thanks in advance.