Mirena coil and dizziness

I've had the mirena coil for four months, I'm still bleeding irregularly (period every 8 days) and lots of spotting. I've been dizzy for months, I'm feeling very low, I have water retention and a lot of lower back pain that feels like a pinched nerve so I'm battling to concentrate on work. I really want to have it removed but I'm terrified of going back to the alternative of extreme heavy periods that made me anemic.

I've had the hormonal mirena for 14 months now to reduce endometriosis symptoms. My periods have reduced in length (used to be 3 weeks) and happen irregularly and the pain has settled during these. I have however noticed continuous weight gain since I went on it, despite very little changing in my diet and exercise. I've always stayed at a very stable weight and now my breast have nearly doubled in size and my weight in general continues to creep up. I have tried upping my exercise with no improvement in my weight. I'm the heaviest I've ever been, except for pregnancy. It's a huge price to pay for a reduction in endo symptoms. It's very frustrating.

My first year of the coil seemed to be okay. Took a while to get used to and on the grand scheme of things after about 3 months my period pretty much left.. but in the last year, I’ve been getting symptoms of anger, forgetfulness and generally feeling checked out. Going to speak to GP to find another option.