What are the signs she wants you to ask her out?

[breakingdown]

I know she is crushing on me big time. I kinda like her too and flirt with her in a very healthy way. Recently she asked me what I was doing this week and said she is going to her friends B'day dinner. I told her I was working all week and then she ever so gently and in almost an inaudible voice said that 'come if you're free, if you want' in a very nervous tone.
Her voice was so low that I just carried on with my stuff while we were talking and then the topic changed. Literally recalled after two days realizing that I've turned down an invitation!
Ever since the whole week she is just posting stuff on FB how good her week is going (coffee, B'day dinner etc) and also her recent picture with her mom at a restaurant saying she was alone on a Friday and thanked her mom for being there (kinda cute but not sure what was she expecting me to think of it). She usually never posts on fb but this week she has been unusually active, don't know if she trying to show something?
Since I very unintentionally turned her down, how should I go ahead and ask her out?

[kayciesimon]

watch for body language and how she reacts when you flirt with her. is she leaning in? touching you? complimenting you? flirting back? or is she scared? nervous? stays away? gets creeped out?

[Anonymous]

If she is crushing on you big time, she definitely wants you to ask her out. Duh.

[Kenny_22]

Next time you see her just be like "hey, sorry i couldnt hang out last week, wanna do something this week?" if she says ya, then you just asked her out