If you had unprotected sex 4 years ago and your HIV Test was negative after 3 months, and later both you and your wife again tested negative during pregnancy, the chances that you have HIV are extremely unlikely. HIV tests done after the window period (about 3 months) are considered reliable. Since multiple tests over the years have been negative and your child is healthy, there is no indication that you have HIV infection from that exposure. If you still feel worried, you can take another HIV test for reassurance, but based on the information you provided, the risk is very low.