???Question???

Jessica
OK...... Had my first child on the 21 of July. Bleed for a few days after having her, got my period the first week of August for a week. Had another period a week layer, then had my period for September. Was supposed to start again the first of October. Has not shown up!! Was only on BC for about 3 weeks, due to insurance issues. Have had unprotected sex with my so. Kinda worried to take a test. Not sure of I should, or if I should wait a bit longer. How soon after giving birth can you get prego again??? Any advice would be very helpful.