Do you think it is possible to apply for lmo when i havent worked for them for a long them?
Yes, they can apply now for the LMO. they could have also applied before you started working. Doesn't matter how long.
I read on cic website and it said that if i'm on pgwp, Employers hiring former PGWPP participants in higher-skilled occupations are not required to conduct recruitment or advertisement efforts,
Yes, this is true, your employer does not have to demonstrate recruitment efforts. You must click on the link that amikety provided and read the information there, show it to your employer.