I'm sure you didn't do anything wrong, however, I think you're spending too much time overanalyzing when you can simply have a conversation over the phone to address this issue directly. Regardless of what the problem is, if you guys can't communicate like adults, your relationship is doomed to fail.

She might want to know how you feel after you got intimate, but she risk sounding clingy by bringing it up. If this is the case, you can express how you feel about her and you're not just looking for sex (if that's the case). Let her know that you notice something seems off after the intimacy and that you really like her and you'd be okay with dating without sex if she's not comfortable with it at this stage of the relationship. If you're putting in all this effort and she's still not interested in you maybe it's time to move on.