THE PILL AND WEIGHT GAIN OR SLOW WEIGHT LOSS

So just a little background. Over the past 10 months I've lost 80kg (about 177 pounds) and 3 months ago I started the pill. Both for contraceptive purposes and also to help deal with the pain of my period. Since then, I've continued to lose weight, but it has been slower. Has anyone had this problem and does anyone know why it happens? I'm currently not sexually active so I'm thinking of coming off it for a little bit. Thanks xxx