I haven't read all the posts because I got a bit lost but I think you and your T are actually talking about two separate things here.

1. Whether you, as a person, are worth caring about and should naturally expect to be cared about.
Your answer to this is shaped by your beliefs about yourself and how you imagine other people regard you. Your T's answer to this is shaped by her experience of you. If you think negative things about yourself, they are beliefs and not facts. Your T can see through them!

2. Whether the people in your life right now are actually doing a good-enough job of caring about you.
Your answer to this is shaped by your experience of these people. Your T's answer to this is shaped by her beliefs about these people and how she imagines they might behave on the basis of what she knows about them and about you.

Thing is, this isn't cause and effect. It isn't the case that 1 if you are good-enough and worth caring about then 2 you will experience good-enough caring from other people. It's so easy to mix up your opinion of yourself with how other people treat you and assume that if you're being treated badly it's because there's something wrong with you. But if your relationships aren't good-enough, it doesn't mean you aren't good-enough.

So your T can be wrong about the quality of your relationships, as she hasn't seen and experienced them first hand. But she isn't wrong about the fact that you should expect to be cared for and that this should be happening.

If I was you, I think I'd probably tell my T that I find it invalidating and upsetting because she seems to be confusing whether you SHOULD be cared for and whether you ARE. The fact you should be doesn't mean you are, which is where she's going wrong.

The fact you aren't doesn't mean you shouldn't be, which is where you're going wrong.

Hope that makes some kind of vague sense...