I'm new , and I don't intend to intrude...but perhaps you need to focus more on what you have that is positive in your life. The T-relationship is indeed a real relationship, but it is not meant to "give you what you need." And I find it interesting that you are so focused on a "T" when IRL you have some relationships.

1) You stated that "your parents LOVED you" -- you know this, but yet you are focusing on getting "love" from your T, who in all reality is a paid support and relation. Her "love" or "caring" is a business venture. You pay her to "be/respond" a certain way. When you are "healed" or run out of money, she is gone. Parents and family are not.
Perhaps, you should be addressing your feelings about your parents, instead of focusing on your feelings needed from T. If your parents are alive, address it with them if your relationship is ok or address this issue in therapy.

2) You stated you were married. Support, caring, initimacy, should come from this relationship as well.

3) You stated you have children and grandchildren. Being with a child can bring "the child out in you."

I know the IFS model and I know what Schwartz teaches. It is a good method for many things. I am not so sure it is a proven technique for Borderline PD or "lite" Borderline PD because it does create incredible transference which is questionable in working with BPD. (ie you child part needs to hold the hand, needs to get a hug, and one gets stuck in the child part constantly, manipulating the T to respond to child part needs constantly, etc)

I guess what I see as an outsider looking in, is a person who has many relations IRL, but is trying to create a relation with a T that can not exist. All the parts in the world can try and get their needs met by your T, and you can learn slowly for your Self to fulfill those needs, but instead of using the business T-relationship, perhaps you should be working within the real relationships you have.

Particularly if you have been down this road with other Ts, multiple times. Aren't you getting tired of chasing a T?
You have people that love you!
If you have people that love you, that is where to start questioning what can improve in your life.
Your T will never love you -- remember it is their job and their caring and love is based around that fact. It is not unconditional.