I totally know what you are describing here: it's when you commit to things that you wouldn't otheriwse do because you have short bursts of confidence...I am the same way. It gets tricky though, as you've already committed to something.
I suggest you follow through with the plans you've already made, and then just try your best to restrain yourself from making such plans again. When I'm very socially anxious or jittery, I will often say I'm sick...which isn't far from the truth, and if you do not have the courage to follwo through with that plan, just say you aren't feeling that great. You should at least try to follow through, through, as you will let the other person down if you don't.
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Given a “tentative” diagnosis as a child as I needed services at school for what was later correctly discovered to be a major anxiety disorder.
This misdiagnosis caused me significant stress, which lessened upon finding out the truth about myself from my current and past long-term therapists - that I am an anxious and highly sensitive person but do not have an autism spectrum disorder.
My diagnoses - social anxiety disorder and obsessive-compulsive disorder.
I’m no longer involved with the ASD world.