HI,
   I understand your concern.   
Fertility in TPHA +ve patients depends on the stage of 
Syphilis . The mother's infection can cause difficulty in conception, 
abortion, still birth or congenital problems. You give history of miscarraiges/ectopic pregnancies.
  *  Please get fully investigated before you try for conception, to assess-
       - the status of disease in your body after taking treatment .
       - The general condition of your health,
      - status of your genital system from conception point of view( Ovulation study,
HSG for patensy of fallopian tubes )
   * Take full treatment as per the results of investigations. Confirm eradication of the disease from your system  , Be under care of an expert gynecologist & plan for a baby & with systematic efforts you will get a child you dream of. I wish you all the luck.
    Thanks.