For the possession charge, you're looking at a maximum penalty of $1000 and/or up to a year in jail. For the paraphernalia charge, it's a maximum penalty of $500.
Maryland pot laws are summarized here.
Presence of THC in one's system is not detectable by shining a light on your eyes. It's more likely that you smelled of pot, so the office shot his mouth off to try to scare you.
That he claims to have ID'd you with a PA driver's license when you don't have one is problematic.
You'd do well to consult with an attorney.

