I did receive a reply after all (a couple of days later). I was very happy about that and I could imagine T would say that there was no need to apologize... which she did.
I do agree that lots of therapists either don't seem to like email and others rather want to discuss things in sessions and in person. I do get their point very well. It's also the reason why I try never to send things that sound very urgent by email. As if to not leave T the option of not responding...
Still, it can just be very helpful if, when it feels necessary, you do get a reply that eases your mind a little bit. I'm glad about that.