Trouble meditating

A few days ago, my therapist told me I should meditate daily and gave me a sheet with some exercises for that and showed me how to do it, since I seem to always be stressed without having any reason to.

I found a space in my routine I managed to fit meditating in, but I'm having so much trouble with that. I'm trying to meditate and concentrate on clearing my mind, but the only thing that does is make me hyperspace of everything that touches me, my clothes and the surface beneath me and by hair, and it's disgusting and overwhelming and makes me want to cry.

Then I can concentrate even less, because my mind keeps coming back to 'when will this finally be over' and 'this is such an easy task, why am I so incapable' and I want to cry even more.

Then there's also one other specific exercise, which is the worst one. I need to exhale, then cover my ears and hum without force (?, dunno if that's the right word, english is not my first language). Covering my ears like that makes me hear disgusting sounds, if that makes any sense.

Does anybody have any tips or advice for me?