Suggest Treatment For Irregular Menstrual Periods

dear sir, I am shilpa my age is 23 i have a irregular periods if i take a tablet then after three days my period comes.i consult many doctors they told regular excesise make periods regular.i am doing it but no use.scanning also done they told water bubble in uterus.please give me a solution am frustrated,i fear there might be problem in my pregancy after marriage