I'm really interested in a girl in my grad school, and we text quite often, maybe about 25% school related things and 50% social things, and the remaining 25% fun/flirty. She initiates just as often as me.

I rarely use emojis, but generally say lol/haha when she says something that I actually think was funny. Earlier she asked me if I wanted to join her work group for our new class, and I said yes because I didn't have one yet and then said "Thanks ____ :)"

After I typed the smiley face which was I just intended to be friendly because she reached out to me and I appreciated it, I can't help but think I came off like a pussy... rarely am I sending "nice" texts like that but at the time it felt right only in hindsight it didn't.

Her response was simply a thumbs up emoji which really tells me I fucked up. How to recover from this or am I overanalyzing?