I could have written much of your post. I have been in therapy for 6 months and if I had been replying to your post last week I probably would have been saying I have recently had a breakthrough with trusting my T and feeling able to be vulnerable but last session my T said the portcullis had come down again and he was right. I suddenly didn't trust him again. He says I'm like an iceberg (only 1/9th exposed) but he also said resistance is ok, it's a defence mechanism and it's not a bad thing.
Trust in your instincts and let the trust in the relationship form organically. It will take time and have hiccups but if you push yourself too soon to trust you could end up frustrated or more vulnerable than you are ready to be.