First of all, this antibody is found in about 1 to 2% of perfectly healthy people, and it increases in incidence with people above the age of 65. Seronegative rheumatoid arthritis is also found far more frequently in people with the juvenile form of the disease (acquired in childhood). The longer someone has the disease, the greater likelihood there is for the antibody to appear, though in some people it never appears.
The one major difference that medical studies have found is that people with seronegative rheumatoid arthritis seem to have less overall joint erosion and damage than people who test positive for the antibody, and usually do not develop nodules under the skin, as the positive group tends to do. Otherwise, the symptoms and progress of the disease appears to be similar in both groups. So, if you test negative for the antibody, you will still likely experience joint swelling, stiffness, and damage, but not to as great a degree as those who test positive. It may be small comfort, but it is some consolation nonetheless. If you are negative, appreciate the fact that you've been given somewhat of a reprieve--your symptoms, though they are there, could have been much worse, so you are among the lucky group that may be able to retain your joint function and independence longer than other patients with the disease, maybe even throughout your entire life.