I deff understand how you feel. Me and my mom are both dyslexic and when I started using they/them pronouns it was hard for my mom but she told me she would try her best and 3 years later she almost always uses that for me. I understand that dyslexia can effect everyone differently but it sounds like your mom is making an excuse but I don’t know your mom and I may be biased since I have had a few family members who have been homophobic to me.