I can't understand my girlfriend?

So recently me and my bsf started dating. We have been best friends for more than 5 years and there were times that we were really really close and times were we hadn't spoke for almost a month. Both of us didn't actually make it a problem. Two or three weeks ago i kinda confessed my feelings to her and she said she was feeling the same for years. For me deep inside i knew that i had feelings for her but never actually accepted it. I was kinda a playboy type back then. But this time its different. I really dont wanna mess things with her and make a healthy perfect relationship.
Here is the problem
She is offline way too much. Like we meet up, hangout once or twice in a week and i really enjoy these times. But when it comes to online its incredibly hard to chat with her. She is responding hours later when i text her. I mean she was also like that when we were friends and back then i didn't care about this that much. But since we started dating shouldn't she supposed to at least check her phone more often. I also dont wanna make it a big fuss over something like this since everything else is going pretty well. Also sometimes i feel like she is kinda cold to me even tho she acts exactly the same. IK this one is me being paranoid so i dont really care. But i really need some advices.

PS: I am 100% sure that she loves me
Also sorry for my mitakes since English is not my main language
I can't understand my girlfriend?
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