How Can Irregular Periods Be Treated For Successful Conception?

Hi,iam vishala,from chennai,i have a gynec problem,i dont get my periods regularty,i mean i dont even know if iam getting my periods if i dont take medicines,now i want to have a baby,but,my problem is,i dont get periods till i take tablets like modus 10,i took treatment fr 3 yrs,used tablets like crisanta,and other similar tablets,but no use,please help me,i want to concieve now,iam 28 yrs old?