welcome to HealthcareMagic
at your age is a common problem and the main reasons are hormonal
imbalance and PCOS
(polycystic ovarian syndrome
).I guess your Gynaec has investigated you and given Diane
35 for three months so that it will regulate the hormones as well as help regulate the periods.Do not worry it will make your periods regular.As for the weight gain you fear it is a side effect of all hormonal pills and it can be seen in few cases and not all.Also please understand that the weight gain or any side effect of the pill is temporary and usually reverts to normal once the pill is discontinued and the side effect of weight gain will happen with prolonged use and not 2-3 months.