You were booked with the tampering charge because the amount of marijuana you had was a misdemeanor offense. This tactic is used by the DA to get the biggest penalty for the conviction. You need to hire a lawyer. You may be eligible for a diversion program which will prevent you from actually being charged. Good luck.
You are facing the tampering charges and also could face the misdemeanor possession of marijuana. Montgomery County has been attempting to streamline the charges by rejecting the lesser charges and going on the higher charge; thus your felony tampering. Because you have no criminal record to speak of you could be offered a deferred probation on the felony. The state could even agree to go on the misdemeanor and dismiss the felony. It is important to hire an attorney to research the stop issue about your light. Police have to have reasonable suspicion to pull you over; if he or she can not articulate the circumstances of the faulty light, you could possibly have the case thrown out. Best of luck!