Accept that you will never know whether she is interested until you take action, don't fuck around with it either, go up to her, be confident in the fact that you could provide a great experience for her in romance and life, look her in the eyes and be a man about it, tell her the truth, that you took time out of your day to talk to her because she looked attractive and you want to get to know her.

This is like the biggest issue I see on here and in men, everyone wants to know what the result will be before they make the play. They have it the wrong way round, you take action to find out what the result will be, you don't find out what the result will be to take action.