It's completely normal to mourn the loss of a relationship.
But keep in mind that you are mourning what you'd wished it had been and not the reality.
You've done the right thing by ending the relationship, no need to question yourself.
You are an intelligent, sentient person, so it's normal to question things or have doubts... you are seeing the shades of gray and not painting the picture bllack and white which is good.
Find pride in yourself for respecting your boundaries and limits... you deserve a therapist who is more engaged with your story and remembers it from one week to the next.
Only about 20% of therapists are excellent, 20% are terrible and the other 60% is somewhere in between.
Keep trying different therapists till you find one that is excellent and really fits with you.
No need to reproach yourself for shopping around.
Therapy is an investment and you deserve the best!