She said yes to a first date. So why is she taking a long time to read/respond to messages?

Me = M24

She = F22

Let me get this out of the way: yes, I overthink. A lot. Also, I know this might come across as entitled to attention/response. That's really not how I feel; I'm just interested in people's thoughts.

I have had a crush on this person for a few months and wondered for a long time if it was reciprocal – I thought there were signs but who knows with these things. We're friends, in the same social group and get on well but aren't super close. I finally decided to just ask her on a date. Obviously, we're still in lockdown. I asked her through Messenger, said let's go on a date when things get back to normal, or maybe video drinks at some point?

She took a few (agonising) hours to respond and then said yes. It was a fairly enthusiastic yes: she said it was a "nice surprise", "sounds great" and is "looking forward to it". She said yes to both a video and real life date.

We've been messaging back and forth a bit but she takes a long time to read and then respond to my message, like 5-6 hours, though she is online. At first I thought, she is just busy, but we're in a separate group chat on Messenger and I can see she reads those messages, but not mine. I'm not going overboard either – no double messages, and we've only sent a few back and forth since I asked.

So my mind is telling me there are two possible reasons: she doesn't really like me, she said yes more out of a "meh, why not," than a real attraction – so is she actively avoiding my messages because she's really not that interested? Or, she does like me but doesn't want to seem too eager, so is taking her time with responding.

Hmm, on reading this back something is telling me …stop overthinking…

Any thoughts, feedback, harsh words for me?