Hey dude, relax. I did exactly the same thing you're doing about 5-6 years ago, and now I'm a pilot. I didn't go to the academy and I didn't have 99s in everything. In fact, ROTC is the easiest route to getting you a pilot slot. True, the academy grads get top choice on getting the slots, but if you work hard enough, it's pretty easy to get one out of ROTC. You pretty much just have to be qualified and not an idiot.
Here's what I did:
I took the AFOQT, did mediocre 50's to 60's, had a decent gpa from going to school part time while enlisted (Avionics on B-52's at Barksdale), I applied for ASCP (I have a good friend who's doing the exact same thing right now) and was accepted. I chose my school, worked my ass off there and got good grades (the most important factor out of ROTC getting a pilot slot, BTW, and I say that because that'll also affect your commander's ranking) retook the AFOQT after studying pretty hard the first summer I was there for it, and did much better since I knew what to expect and all. In hind sight, the AFOQT is only a small part of getting your slot anyway. Tried hard in ROTC at my school, and then started all over working for what I wanted when I got to UPT.
It's a long hard process, but it's totally worth it.
Here's my advice: Don't listen to whoever has been telling you that crap. They're probably from the academy, and have no idea how the ROTC program even works. Call an ROTC detachment and talk to one of the officers there and they can (or at least should) tell you exactly how the pilot selection process works for ROTC cadets, if you want to know. Also, ROTC's pretty gay, so is any other AETC training you'll do, so keep that in mind when you get there.
If you have any more questions, send me a private message, or whatever they call it here.
Big Bear