If you have small finger joints pain/difficulty getting up from bed and early morning stiffness of joints which relieves on working during the day then only you should get your RA factor/anti ccp levels done. These tests could be negative also. Osteoarthritis
usually does not affect young age group. Also the kind of pain
you are telling was associated during pregnancy and is continued later till 4 years can be associated with some clots in your blood stream. That needs to be evaluated properly with detailed history and examination.