Consider journaling what it is you want from your relationships (and interactions with other people), and what you don't want. For me, I find writing this stuff out gives me better clarity and makes the thoughts swirling in my head more clear.

What is happening in your interactions with other people (often times, there's a pattern, and that's one reasons there's a call for boundaries, because it happens over and over) that you don't like?

One thing about creating a boundary, is that creating the boundary may be easy to come up with, but hard to stick with. For both parties. So you may come up with something, like (and this is just an example) "I will not engage with people who treat me poorly and make me feel badly." But its another thing to actually implement it and stick with it, especially if there's something else you may be getting out of the interaction. Or, the person may be your parent, and then, well, if they treat you badly, how do you get them to treat you well? You'd be better with limited contact if you were a child. And if you needed them, say, for financial support as an adult, you'd have to also use limited instead of no contact.

Does your therapist have any ideas for you on how to create better boundaries? I say ask your therapist how as well. Especially because they are the one who brought it up. And do you have specific boundaries with others that you WANT? That was not clear to me in your OP. I have read and responded to some of your other posts, but I also don't want to assume, or bring up something that may be inaccurate for you.