Should I be offended? She cropped me out of the picture!?

[why]

I went to homecoming with a few people I'm kinda friends with...we're nice to each other....but I mostly know this one girl "a". Me and "a" have a lot of classes together but we never really talk...maybe like once or twice...even though i'm kinda socially awkward she was nice to me, she's kinda shy herself but i like that she's so nice and not judgmental or rude at all like most other pretty girls...But the other day i asked if she was going to homecoming and she said she was so i asked if i could go with her and tag along since i dont really have that many friends...she was hesitant and was like "umm...yeah okay." then she gave me her number and when i got to homecoming i texted her and she told me to meet her at some table...then there she was with all her friends...

So I went with her and her friends...but i had other friends their too and i would go back and forth from people to people that I know,,,I didn't just stay with one group...

Well when I was with "a" and her friends...the entire time i was quiet, playing with my nails or my phone, i didn't talk to anyone...and 'a' is pretty reserved and shy so she didn't say anything to me except hi when i got there...some teacher person told us we should take a group picture because everyone looked so nice. So everyone got up and i just joined them even though i felt annoying since i'm not even good friends with any of them but i do KNOW them, i've talked to several of them before...i stood beside "a"...

then today i went on facebook and i see that she posted the picture and put "with my girls ♥" but i was cropped out of it...

should i be offended? or am i being too sensitive...we're not even really friends but i still feel sad...
and i feel like they don't really like me anyways...people tell me i'n really awkward and annoying, too insecure and weird...

i talk a lot because im always nervous, i never know if people are annoyed or tired of me, so i just keep talking since people dont like quiet people...but no one likes me even though im really nice, i always compliment people, say hi to everyone i know in the halls evenif i hardly know them but people think im weird and a loser

btw im a senior in hs

and she doesn't know that i have a facebook...i made a fake account so that i could see people's pages and i added her...then i saw that picture

[Boces]

Why is your grammer so horrible

[Juval Deluval]

Firstly, to the last person that answered, that's pretty hypocritical coming from someone who misspelled grammar and left out a question mark.
That's a tricky thing to deal with. I wouldn't be offended, she probably just wanted a photo of her and her best friends. It doesn't mean they don't like you, just that you aren't fully in the group. I think you need to find people you're more comfortable with, and settle into a group with them, rather than tagging along.
Good luck