6 months post getting my Mirena

So March I got my IUD put in, and April I had a period missed one in may and June, got one in July, missed one in August and had a extremely light one early this month, have migraines, gained all my weight that i lost after i had my daughter, feel nervous a lot and get flutter in my stomach( i saw on one site it was called uterus spasms or something) Has anyone else experienced any of these same effects, especially the every few month periods, and flutters.