...tune it up, plug it in, AND (just) start playing that Bass! I can relate to the "Paralysis By Analysis Syndrome" (how 'bout "PBAS" over your "P-BASS")?
From all the info you've already provided, it doesn't seem that you got a "ringer". Try to relax and enjoy it, see if you aren't inspired to come up with a new bass line (or sit yourself down and learn the bass part of a favorite song...). I realize $225 is a decent chunk of change (not all of us can readily if ever afford $1,000-2,000 or more outlays for every up-the-quality-ladder instrument of affection), however, if after say another 2 weeks of solid time with it, you are still experiencing buyers regret, you could always sell it locally on CL for $200, probably even listing it for your original $225, maybe more (250?)! Bottom line is that in any case I'm more than fairly confident that you haven't "lost/burned" two-hundred and twenty-five dollars. Also in the meantime maybe you could have a more experienced bass "guru" or local shop tech give it a once-over for (hopefully) more affirming peace-of-mind.
In my less confident days, I once brought a bass I bought elsewhere to a local GC and asked the guitar tech (who was adjusting another guitar) if he wouldn't mind giving it just a quick visual inspection. I left it with him and walked over to browse the racks and much to my surprise just a few minutes later I looked back over to the set-up table and the guy had it on there and was making a couple quick/minor adjustments, then putting the bass up to his ear, etc. he's says: "looks good, sounds good". I plugged it in and while I can't say for sure the intonation sounded "drastically" different to my ears, it played a bit more easily/comfortable. I asked him if there was any charge per se, he just shook his head and was already onto another instrument. Granted that may not happen for you--and in no way was I expecting or asking for that myself, but the guy's rightgeousness is self-evident, and I felt more assured about my purchase at that time.
PS--I bought an instrument cable then and went back another time and bought a tuner (or vice-versa) just to try and hopefully "balance" the scale at least somewhat, and in any case I try to recommend to others I come into contact with locally to at least give that GC a try with their patronage and I certainly would consider buying either a used or new bass/amp/other gear if the right piece was there for me.
Anyway, sorry for the tangent. Onward, Ye Son: "Play That Bass"!!!