Intolerable to pills and now getting mirena in 2 weeks and very nervous

I am new to this forum - I apologise if I have posted incorrectly. Sorry that it is very long also.

I am 23 and am having a Mirena Coil fitted in 2 weeks. I have not had any kids. I am extremely nervous about it being fitted as everything I have read is pain, pain and pms!!! There does not seem to be any positive stories - so I think why are they even considering giving me this?

Brief history: Basically from the age of 16 I began having very heavy periods and they were very painful. They have became considerably worse over the years and now come with a whole entourage of symptoms each month then when they are gone I am back to my happy self again. They are regular like clockwork but really unbearable - very heavy, I am anemic a lot because of this, very painful and last about 7 days, first 3 days are the worst. The week before my period is awful - complete pmt - severe moods, bloating, ravenous for chocolate and anything fatty (I am usually a really healthy eater), cramping a week before, even cramping after orgasm the week before. It is causing problems in my relationship with my boyfriend and my family because at that time of the month they now say I am "unrecogniseable". I just become a monster and its really upsetting and difficult to deal with.

Anyway I have tried pills then had to stop because I suffered migraines, and the combined pills made me vomit permanantly. I tried tranexamic acid, mefanamic acid, norethisterone you name it I have tried it for the bleeding! All made me sick and made me feel worse. Last year I was prescribed Cerazette the mini pill - this was AWFUL - my legs were swollen, I had a permananent headache and I felt like I had high blood pressure. I exercise and eat healthy yet I still suffered these problems. Usually 2 hours after taking Cerazette I felt as if I had just taken an opiod or something because I felt dizzy and sick. Anyway I stopped that then the doc prescribed me Femulen. This was another horror pill - I was bleeding constantly and was having 2 heavy periods a month for about 4 months. I could not handle it - pmt was reduced significantly though but the bleeding and cramping were still unbareable.

Now the doc is saying only option is Mirena - especially due to my migraines and PMT. I am so worried though that this will make me a looney or depressed or just bleed constantly. I have read SO many bad stories and I dont think I can bare another bout of bad hormones I actually think my boyfriend and family will just give up on me as I become so nasty. Also the anemia is a big issue - I cannot afford to be anemic again.

Does anyone have any type of advice? Have you experienced anything like this? Any tips on when having it fitted to make it less painful (doc has told me to take ibuprofen and they are using an aneasthetic gel ). Any advice would be appreciated and I apologise for this being so long.