Ok so I started texting this girl from school about 2 weeks ago it was going well and we were flirting but then we became 'bestfriends' then the next day we went on a drive and we just sat and talked for a few hours

2 days after the drive we were still texting but I decided to ring her and ask her to go to the cinema but not as friends but on a date she agreed and we made plans the problems started the next day

Her:I can't go to the cinema next friday it's my mums birthday sorry
Me:wanna just go on Tuesday then? If you don't wanna go just say I'm not bothered
Her:will you not be annoyed? My dad doesn't Like me going out in the week
Me:no I won't be annoyed I'm not bothered although I do like you
Her: let's just be bestfriends then?

I agreed then we texted for the next few hours unitill she didn't reply to one of my texts so I decided to freeze her out I didn't text her at all yesterday and I don't plan on texting her today how should I get out of the friendzone and stop her from flaking because I know she mustve liked me in someday if she agreed to go on a date in the first place also how did I mess up in the first place cause I don't wanna make the same mistake again. Thanks