I Have Been Tested For RA On Numerous Occasions With

I have been tested for RA on numerous occasions with 2 different blood tests and one tests negative the other tests are high over 100 for RA however since it is affecting my knees and larger joints and not my hands there is conflict between Drs if its truly RA Im confused can I still be positive with RA and it affect my larger joints first and not so much my hands first?