You need to be more forthcoming with your feelings to her.
Flirting with her is alright, but it's not always enough, especially if you're too subtle with it.
You can often just come off as just being friendly.
It takes some guts, which is why it's good that you're thinking of asking her out, but you should definitely make stronger attempt than flirting to actually let her know what you think of her too.
And about the depression, you just need to pick up some confidence.
And if you can't do that in time, then just do the blind-luck of asking her out.
If she says yes, you'll be pretty damn confident and a lot less depressed then.
And if your depression is caused by the fact that you're not getting much back in the way of feelings, then think of your feelings for her differently.
While I'm sure that you do really like her, don't tell yourself that it's love just yet.
Love isn't worth it if it's one-way.
You do care for her, and you'd be ecstatic if you could be together, but just know that you'll be able to get on if she doesn't share feelings for you. You will definitely find other people whom you enjoy just as much as her, and knowing that if it doesn't go perfectly according to plan that you'll still be fine, you won't feel so crushed if it happens.
You don't want to put all your emotions into a person before there's any sign that they might be returned.
Put a plastic flower in there also for her to keep as a memory of that night
This is a good idea.
Also of note, going with the idea of gifts, don't shower her in loads of things and don't dedicate all your money to her.
A lot of people do that, and it's not fair on you yourself.
Give gifts, but don't give away everything.
