Hi, Marujita, since you have been asking so much about this, and are clearly so worried, have you looked into getting a set of vaginal dilators? They are sold for women with vaginismus. There are plastic sets and silicone sets. You could talk to your doctor about the problem and see if anything about the dilators would be contra-indicated. Here is a link to just one of the companies that make them. https://www.soulsource.com/collections/silicone-vaginal-dilators/products/silicone-medium-set . It might take some discipline on your part to actually use them, but given how much you seem to be worrying, maybe it would solve your problem.
I do believe it is likely to be a bit difficult again for the psychological reason you are fixated on it. I don't know how to relax you and this all seems so mechanical like you aren't even enjoying the process and so anxious about it. I'm kind of wondering why you want to do it. I'd personally begin making meaningful emotional connections with someone you are more romantically involved with so that you can relax more. good luck