The reality is, is that you have a chronic condition not recognised or known and that's within the medical feild itself! Its very demoralising to go to your GP or A + E and people treat you like dirt which in your mind is supposed to be a caring tradition, yet on average, it takes 7 years to get diagnosed and then to top it all off, when they do get it wrong and Endo is found, they don't even have the manners to say sorry, when yesterday they were telling you that it was all in your mind!
I'm not sure what I can say to make you feel better? Its not fair! Yep! You didn't ask for this condition? Your surrrrrrre right there honey! What to do or say? Acceptance. Boring I know. With this condition, sex maybe painful, you might not be able to have children. You also might not be able to work or have the career that you want. You may never finish University. You may also lose friendships and relationships. ( This is worst case scenario)
However many people maintain relationships and get married. Many people also have children. Many people find a good Consultant who is patient and kind and is prepared to try different things out , send you to see a pain Consultant etc etc and its all hunky dory.
What you are going through right now, everybody with a chronic condition goes through every now and again You have every right to be angry and vexated about your life! You are 18. You are supposed to be lying the in the gutter drunk, not lying in bed with a mass of hot water bottles and having yet another cancellation. The situation is simply horrid!!!
My get out card for myself was, was that I was doing everything I could do. So for me it was about reading science and medical papers, looking at alternative methods in terms of pain control, looking at my diet and lifestyle, changing GP and perhaps Consultant. Sitting down with friends and family and explaining what you have and what you need from them( understanding is normally a good start!).
Since I don't know you and what you have done, you may have already done the above already, so I apologise for repeating mantra.
If anything, many of us have been there, we sympathise, the situation is horrid! But I hope you know that we are out here, having gone through exactly what you are going through right now and to know that there are people who have got better, got the right treatment and have gone on to have happy lives. So don't give up.
Take care and big hug.