How to tell if an interview went well?

I recently had a webex interview with a boutique and shortly after I sent a thank-you note. I had talked to a few members of the firm before and the technicals were all very easy. I try to make the thank you note personalized as I am interested in how their job/life is going and they responded back with a couple of sentences and some exclamation marks after the interview. I know gauging a thank-you reply is difficult as I have read many posts on here saying you will just never know. However, this was at a boutique and I felt that I was able to connect with them well and they are pretty big on fit. Also a bit scared that I came off as a bit too eager even though I am genuinely interested in their vertical and business as a whole. What do you guys think? Any feedback would be greatly appreciated :)