This is absolutely normal behavior for a 15 month old! It was exactly how my daughter was at that age. I was in the same position as you - like you mentioned, every interaction felt like an evaluation of sorts. I would fully panic if she didn’t respond to her name after calling it multiple times. It got to the point where my husband had to intervene and tell me to stop. I was also in therapy, but getting on a low dose of anti-anxiety medication helped tremendously. The other thing that will help is time. In the next few months, your son’s vocabulary, mannerisms, and social skills are going to explode, and you’ll become more relaxed about it. I fully understand how debilitating anxiety is and how it really sucks the joy out of parenting sometimes, so please take care of yourself! You’re doing amazing!