I think you are right to mistrust your doctors--I know that sounds cynical, but AI disease is darn difficult to dx, and rheumys are wrong sometimes. That being said, with a slightly positive RF, and joint pain, it sounds like something is going on with you. It may not necessarily be RA, but could be any of the connective tissue diseases. Like you, I have a slightly positive RF with symmetrical joint pain. My official dx is RA, but rheumy is the first to state I don't really have RA. At this point, he really doesn't know what it is, except that it is something inflammatory, and it responds to typical RA medications like enbrel and mtx. Without an RA dx, my insurance would never have agreed to pay for enbrel, which is a very good drug, so there is a rationale for having a dx, even if it's not the correct one. When my rheumy prescribed ultracet, he made sure I understood that it would not be a good thing to take just ultracet because it does nothing for the inflammation; just takes the edge off the pain. Inflammation, even low-grade inflammation not associated with swelling, can do disastrous things in your body, including your joints.
Early on, like you, I had good days and had a great deal of denial about anything AI going on. These days, though, it is obvious to me and to those around me, that something ain't right. Rheumy is also getting very aggressive with the meds. I think you're doing the right thing by going on the DMARDs--you can always stop taking them if you're not comfortable. You can't undo damage to your joints once it's already done.
Best of luck to you,
Current dx: Rheumatoid Arthritis
Suspected dx: UCTD/Early Lupus
Current Meds: Enbrel, Plaquenil, Aciphex, Ultracet, Zyrtec, Allavert-D, Zantac, Tylenol PM
Past Meds: Relafen, Vioxx, Mobic, Voltaren, Sulfasalazine, Entocort, Prednisone, Humira, Reglan