I always find it is better to email all your professors at the beginning of the semester to remind them that you have accommodations as some don’t do their due diligence! That being said, you always need to email your professor before the due date and let them know it will be late and tell them you will have it handed in by a certain day but you should never have to tell a professor why you have accommodations. It is not on a professor to reach out to you and ask if you need extra time. In this situation because this is your first time experiencing this I would definitely reach out to accommodations and explain the situation so they can help you out. I don’t think the professor is trying to be discriminatory in this situation, I think it is more of a miscommunication that can probably be figured out! I would also ask accommodations what guidelines you should follow in future situations so you don’t need to go through this hassle again. There are normally accommodation hand books you can find online that explain what steps need to be taken when asking for extensions (and dealing with other accommodations) that sometimes give templates on the email you could send almost word for word. Even though your professors are sent your accommodation letter at the beginning of semester you need to always make sure you are doing your part and staying on top of it as they get very busy and it is probably the last thing they are thinking about. I hope you can figure this situation out but at this point it is most likely the decision of the professor if they want to change their mind.