Texting a girl: advice on a certain issue?

Hello people,

I've been texting this girl I really like and I think she likes me back.

There's this issue that I would really like your advice on. Sometimes our conversations over text last up until an hour or two before she goes to bed, but it just ends abruptly. She doesn't say that she's going to sleep or anything, I just send a message expecting a reply and she doesn't text back until I send her another text the next day. Example, she sends a text and I reply about 3-5 minutes later, and she doesn't reply. However, if our conversation lasts until the exact point she is going to leave, she does say "gtg to bed, ttyl!". I'm wondering if I should ask her to try to say when she has to go more often. In my opinion it sounds kind of desperate and I know girls aren't attracted to that (Even though us guys are desperate, but we don't want to sound that way). It would be nice to have some confirmation that she just left her phone and isn't ignoring me (she has the "read receipts" off so I don't know). Given these facts (especially the one about not getting a reply from her until I text again the next day), what do you think I should do?

Thanks a bunch!!!!

Sincerely,

Just another guy stuck in the dilemma of getting a girl