Grandma lying about my development when comparing my kids lack of progress. Unsure why

My Mom keeps telling me that when I was 4 years old I was speaking in sentences, cutting with scissors and knew my full alphabet and numbers to 100. My twins are 3.5 and aren't doing most of that. I know for a fact that I was extremely delayed in my speech ( my father told me many times I they were unsure I could attend kindergarten on time which would be 5 years old because I was non-verbal). Also in grade 1 the school tried to force me to change schools to a special needs school clearly because I was not catching on. My hearing was very bad and when that was corrected I thrived but that's not the point. My mom knows I feel very bad that my son is severely delayed and probably cannot start junior kindergarten next year. He's likely developmentally 18 months old if we are feeling generous. He has therapists in everything imaginable but it's just going to take more time. My daughter is doing pretty darn good but needs more speech therapy. Do you think my mom is rewriting history to hurt my feelings more? It's really bothering me.