Warning. Quite Lengthy. But Please Help.

So Ive had my Mirena in for specifically 1 year 5 months and my periods have not stopped or lessened except the first few months (around 2- 6) months that I had it. Since then my periods have increased, as well as my cramping and back pain that comes along with it.

My period has always been irregular but became just a teensy bit more since getting Mirena inserted. Anyway I had a period this time of about 13 days (some of those days days not sure if I should be counting due to mostly spotting) once it stopped I had 1 more day of spotting then 4 days of nothing and my bf and I had sex and I started to bleed again but not a lot and yesterday I could not feel the strings so I went to the hospital to get it checked out. Doc said it was fine, just the strings were cut a little shorter than normal and it must have settled more in because the strings were right at my cervix. But when I felt to see for myself I still couldnt feel anything. This morning the blood is really dark on toilet paper and visible when I pee but Im not bleeding and making a mess as I would if I had my normal period. Im confused because Doctor said I was fine but Im not too convinced.