Talk to Gynecologist on Periods/perg

Aoa!i have given birth to my baby boy in last november through c-section,i had my normal periods cycle before my section but after that i got periods apparently delayed for some days then weeks but didn't get them missed every month!(had proper treatment of medication for normal cycle of periods by my dr and she has just precribed me the multivitamins and told me nothing to worry is it normal?)Hence,now this month i got them delayed for 17 days till now,have done urine test but shows negative for pregency please do let me know should i perform test again?or wait for my periods?