Everyone has at least four potential sources of nominations: your two Senators, your Representative, and the Vice-President. You should apply to ALL.
Under the law, only the Senators and Representative in the state/district of your legal residence can nominate you. There are a handful of anecdotal stories of people receiving nominations outside their state/district of residence, but those stories conflict with the US law.
Governors are not sources of nominations.
You do NOT need to know your Members of Congress (MOCs) personally to receive a nomination. Virtually every MOC uses more or less the same process. You can usually obtain the nomination package on-line or by writing to the MOC's office. Your package is reviewed by a citizens' committee made up of people who typically have some connection to the military. The committees for most representatives conduct interviews. Some Senators conduct interviews (well, their committees do it) but some don't -- either because of volume or distance. It is very rare for the MOC himself/herself to interview candidates.
The reason MOCs typically distance themselves from the nominating process is to mitigate charges of nepotism. Thus, your parents don't need to be big donors or political activists, or even members of the same party as your MOC (or even be registered to vote). When I got my nom years ago, my parents were actively working to defeat the MOC who gave me the nom -- so it really doesn't matter.
I'm not naive enough to believe that there aren't ever shenanigans in the process, but in all the years I've been a BGO I've never seen it or heard of it and, to the extent it happens, it's very rare. Almost everyone goes through the process as laid out and earns or doesn't earn a nom based on merit.