If your Riba test is neg, there is almost NO chance you have Hcv. I am willing to say
your viral load will be 'undetected.' A neg Riba almost always means no active virus.
your screening test is probably a 'false pos.'
Welcome to the forum. Many people w/Hep C do NOT know how or when it was contracted -- you'll find in the end that it's really not important in the whole scheme of things. And, don't panic -- it's quite possible that your antibodies fought off the infection on it's own (some 30-40% of exposed individuals spontaneously clear the infection by themselves). The viral rna quantification will tell you whether you have an active infection or not.
If your rna turns out negative, congratulations are in order. If not, and they do detect an active virus by rna, still no need to panic -- Hep C is, as my husband's nurse calls it, an "indolent disease" -- it's a slow progressing disease. And it's good that your Ob/Gyn referred to you a GI -- if you indeed have active HCV, a GI or hepatologist is the specialist to see. They will help guide you in the next steps if indeed you have HCV.
Best of luck.
~eureka