The appropriate time to have had an antibody test done was right when you had your first symptoms. If the swab test was positive for HSV 2 and the antibody test was negative for HSV 2, that would have indicated a new infection – there was virus present on the skin but no enough time had passed for antibody to have been developed. It is too late now, however.
I know you are curious about where this came from, but I think you just to face the fact that you will never know now. Has your partner tested yet? If they are negative, you can know that you did not get it from them.