I am so sorry, Lily

Do you have children currently? If so, mention them in your letter.

Have your RE write a letter for you. Attach it to your letter. Assuming that he/she is supportive of you moving to IVF.

Write down all the positives. If you were sick at the time of the high FSH reading, write that. It appears that FSH, though it's not well documented, can fluctuate based on illnesses and your immune system.

Make sure it is unemotional and fact-based but with enough emotion to make someone like you. Clear, concise. A business letter.

Go get 'em, Lily. I am so sorry you are going through this.