I think it's great that you are so honestly and openly weighing this momentus decision. It's very humane and responsible of you to do so. It takes courage to be so plain about your own challenges and circumstances. I support you in doing what is right for you... But you asked for opinions so here is mine:

I do not think you should have another child. The risk of passing bad genes down to your child is too great. Also, if you have Borderline there could be some issues caused by behavior. So for both reasons of nature and nurture i think it is a bad idea. Instead, focus all your energy into the child you have already. Sound like she is already facing challenges and may have more on the way. You'll need to be available to help her.

Some say life is a gift but for me it is a curse. I don't think my parents did any good by bringing five (5) children into this world, all to suffer. Remember, it's not only what a parent does that can be harmful, it is also what they don't do, such as emotional neglect. I was raised with material comforts and good mechanical day-to-day care and still my brothers and sisters and i are painfully screwed up, one not even making it out of his teens.

Children are a pleasure. It takes a big person, a responsible humane person, to decide not to have them out of care to not inflict suffering on yet another human being.

I'm speaking plainly here because you asked for opinions. It's a subject i feel strongly about. There is nothing i am more proud of (not my degree, career or marriage) than the fact that i have not had children. It cost me my marriage and at 53 i am happy to say i would gladly make the same choice again.

The buck stops with me.

The suffering stops with me.