My girlfriend (17F) takes hours to reply to my (17M) texts although it always shows shes online

r/

This has been going on since me and her got together in January where it would always take her ages to respond to texts although shes always online, it ranges from 2-5hours on average. She does seem enthusiastic when she responds and does send cute tiktoks or instagram reels. But im getting really mixed feelings about this because i have brought it up a few times and wanted to know why, but she always says its because her whatsapp or instagram is glitching and because shes always on do not disturb, personally i find it hard to believe because when she was on a school trip where phones were prohibited, her whatsapp didnt glitch and showed when she finally went offline and whenever we go out, sometimes i take a glance and her phone isnt on DnD. I hope im not overthinking or insecure, its jus that im very conflicted in what im seeing and would like more opinions on this!

tl;dr: she takes ages to respond and im conflicted