I feel you, I sometimes find it difficult to appear interested and enthusiastic without being annoying. Unfortunately observation is a huge part of work experience for us, but that doesn't mean that it isn't a great opportunity
. Obviously you're seeing things different to what I see on placements, but I still try to make the most of everything even when all I can do is watch. I try to take in how patients are restrained, and how simple tasks are carried out (e.g. most vets inject dogs with the needle aiming towards the head when giving vaccines). Try to think of what you've seen a lot of (consultations? wounds being dressed?) and see if you could talk somebody through it step-by-step
Do ask questions and ask if you can do things, if you don't ask you don't get and the worst that can happen is that they say no.
Hope it gets better for you soon