Best friend isn't answering Facebook messages?

[Somanyq&As]

My best friend hasn't been responding to my facebook messages, or takes about 3 days to respond. She is never busy but has her phone taken away from her alot by her parents. However, when she does has it (which I can see by her statuses, or comments on other people's stuff) she never responds to my messages. I feel she is giving me the cold shoulder, because I'm always the one who has to start a convo anyway and ask to meet up etc. If she doesn't want to be friends I would like her to at least say to me, because Facebook is always making me upset for multiple reasons, am I being pesty? Am I a boring person? Irritating, bad personality? I don't see why she would be ignoring me when I last saw 5 days ago where I paid for her cinema ticket and for mine, and paid for her expensive meal at a restaurant out my own savings on the same day, and then her bus ticket home. Wouldn't she at least have the courtesy of saying 'Thank you for paying for me' because I didn't hear her say it once when I was with her. Maybe I should just delete my account...
I feel she only wants to be with me if I'm buying stuff for her.
It's during the school holidays, and I would rather meet up with her before school and hang out rather than me on my own. Tbh I like my own company too but just wanna have some friend time fun, but if it means I have to wait till school... how should I say it? Should I tell her off in a scornful way, or nicely but showing that I'm peeved off??