Coil vs weight!!

I've had the Mirena coil in for a little over a year now, I had it put in shortly after my son was born and I've done nothing but gain weight since! I used to be 11 Stone exactly before I was pregnant, I jumped to about 13-13 and a half during my pregnancy and since having the coil the weight has just piled on, I'm now close to 17 stone, I can't seem to lose the weight I'm gaining but I gain it unbelievably quickly... Has anyone else had this problem with this coil type and is there any advice anyone can give to try and lose this weight... TIA 😘