The person I am unable to say a simple thank you.

The person I am I unable to say a simple "thank you" is my grandmother. Ever since young, my grandmother have always been taking care of me. Whenever she had to leave for work, I would always want to follow her everywhere. When I was in primary school, she would always cook lunch and walk all the way to the school gate and pass me the lunch box. However, as I grew up, I've changed. I no longer follow after her, listen and do what she asked me to do. I speak to her in a rude and impolite way, as if I couldn't stand talking to her. The truth I don't see the need of her knowing the answer. Things got worse when I don't know my answer and she just keep asking, without giving me time to answer her. Like she would just ask the question continuously, a real-life spamming and I find it super irritating. Hence, we became very awkward with each other. Mostly is my fault because I just can't find the right words to explain to her. Even saying a simple "thank you for buying lunch (even though your legs always hurt like hell).", I just couldn't say it to her. So, I just want to say I'm really grateful to be her granddaughter, to be under her care ever since young and up 'till now. I really understand why she would always nag and got mad at me, her intentions and uhh... Thanks, Ahma. XD heh