She lost interest suddenly?

Early 20s male here.. Been talking to a girl who I’ve somewhat known in person for yrs. Recently met up in person (wasn’t a date) we seemed to get along well and conversation was easy to keep going. I’ll be honest I’ve never had a gf and she’s the first I’ve been able to really talk easily too and first I’ve pursued

I’m not the best with hints.. I’m good friends with her brother and he mentioned I should take here out.. I was a bit delayed but finally asked her and she did seem interested then cancelled and we planned another time ( 2 weeks later) We still snapchat.. maybe I send too many and seem clingy?

I wouldn’t say anything too excessive but probably a few in the morning and maybe at night. She always used to reciprocate fairly quick. Now last few days she take forever to open and reply, just enough to keep streak going but thats about it and no words anymore.

Is she just over me? found another guy( don’t think she really dates much at all) or Was I snapping her too much and drove her away?

Figure I’ll cool it off and stop really messaging her for the rest of the week an check in when we planned to meetup and if she flakes from that I’ll have my answer?