I have a severe bicornuate too - had to have my mirena insterted during a surgery to guide it in to the correct side for it to be sitting in. And will need General Anaesthetic to get it swapped when it runs out.
I cannot feel it even though it is squashed in to space which should not normally be able to accommodate it, but there it sits doing a fantastic job stopping my periods, pains, PMT and all that stuff.
Best little gadget i have ever had for period control.
Bicornuates vary in the degree of severity from a complete split of two sausage shapped fallopian tubes, two cervical holes which is when it stopppd developing in to a womb shape early on - through to mild where you do have a decent size womb there and perhaps just a small septum that might not impact on having a pregnancy at all.
Provided a scan shows th mirena in the right location - the pains are more likely to be from the insertion process - stretching and breaking any adhesions and will calm down in due course.
Ask to see the images of your bicornuate so you know for yourself what degree of development there is. it is important to know this, because if it is severe - then child bearing is written off - there simply is not enough room for a bby to grow to term, and the sooner you know that, if you were ever planning family then you need to be looking at surrogacy or adoption.
In milder cases the partition between the two halves may be removable to increase space for baby development.
All female babies should start with two fallopian tubes which fuse together at the cervix and as the development progresses a single womb cavity is formed upwards, with the two fallopian tubes extending from the top corners of the triangle over a few weeks growth of the foetus.
But if your mother was ill or exposed to certain meds or chemicals around 10 weeks onwards in to the pregnancy then development of the womb is interrupted at that point leading to a patially developed womb set up. The later this illness or exposure took place the more it has had a chance to develop in to a womb and the more likely you will be able to carry a pregnancy yourself.
So definitely ask to see the images and discuss them with your GP or gynae if having children is something you had planned to do - other than that, there's no reasons why it should interfere with life, so long as things like IUDs (the mirena) are inserted in the correct location.
Bicornuate has nothing to do with endo it is a developmental issue when you were no bigger than a thumb.
If you were born before 1975 - then look up "DES daughters" and if your mum is still alive talk to her about what she can remember taking during her pregnancy with you. It might be that the malformation stems from DES, but it isn't the only chemical that can cause these issues. DDT insecticide is another - but it could just be that your mum was ill at about the 10-20 weeks of her pregnancy with you.
There are some good illustrations of how the malformities can appear on scans