[ewill3rd]

If you really have 10 psi, no amount of leakage from the FPR would be the cause.
There is only one possibility related to the FPR but... it would never have left the techs bay that installed the fuel rail. If the center small o-ring is left out the pressure will be too low but as I said, you wouldn't have been able to drive it before. Our relays (GM's) are pretty robust. I can probably count on my hands the number of bad relays I have really replaced over the years. (yeah, I'm not kidding)
If the fuel pump runs it should generate higher pressure. The only remaining possiblity I see based on your diagnosis is a lack of fuel. Is there actually gas in the tank? The fuel gage could be lying.
Otherwise I'd say you need to put a fuel pump in it, It is wise to be wary if you are nervous about the procedure required. Look around for a reputable shop and let them do it would be my advice.