Suggest Remedy For Missed Periods

hi,i am 23 yrs old married women. i don't have any children.I am nt getting my periods regularly. in december i consulted a doctor and he said that its due to some hormonal changes and gave me some pills.(sorry, i don.t know the name)after 7 days i got my periods. it was normal.but the same happened in january. then i consulted with another doctor and she gave me mercilon 28.i didn't take it and decided to wait. still no periods. can you help me on this matter.i don't want to use birth control pills on regular basis because we are planning to get pregnant soon. so can i have mercilon for one month and stop it after getting my periods? or do i have to continue it?