A Mirena IUD

Hello, I am 25. I have had mirena in for 5 years and it is due to come out in a month and half. My question is what if i dont get the mirena taken out. For one my insurance has run out, and i called my obgyn clinic and they want to charge over 300.00 to remove it.. what are the reprecussions of leaving it in. I havent had a period in 5 years since i have had it in. And when and if i do get it taken out, before i got pregnant and after i had my son i only went 4 days a week and it was a really light period.. will i go heavier when it is out and how long am i expected to bleed after words. i am a big female meaning 5 foot 2 and 300 pounds. over the last 2 years i gained 100  pounds out of no where and i have been trying to work it off and i am not getting anywhere could this be because of the iud and the hormones it it/ thank u