I am nervous to ask her out, not gonna lie. Reply?

When she tells you to just ask already, she's usually telling you she's open to it. People don't push a guy to ask unless they already like the idea. Your nerves are reading this as a test, but it's more likely an invitation with a bit of a jab in it. Her message is the thing to answer, not your worry about getting it right.

Answer the teasing directly, then make the ask in the same message or the next one. Admit she caught you, keep it light, and name a concrete plan. Her calling you out suggests a direct ask won't land as awkward, so you can be more direct than you would be with someone who gave no sign of interest.

Before you send anything, decide on one plan and one time. A specific suggestion, like the coffee place she mentioned, on a day that's actually free for you, is easier to answer than a general wish to get together sometime. Picking a place she already brought up also shows you were listening, which does more for you than any clever line.

The message should have enough detail that she can say yes without asking follow-up questions, and it should make no-thanks easy too. Keep it short. A few lines is plenty. A long message reads like you're trying to win an argument, and she'll feel she has to respond to every part of it.

Send the ask at a normal time of day, not late at night when it can look like you're overthinking or drinking. If she answers within a few hours, reply promptly and lock in a time. If she doesn't answer, give it a full day before doing anything else, because people often reply later once they've had time to think.

If there's still nothing after a day, send one light follow-up that doesn't repeat the ask in full, maybe a short line about something you were talking about. If that also goes unanswered, stop. Two messages with no reply is an answer, and a third turns a nice moment into something she has to deal with. You can still be friendly if you see her again.