You may not want to hear these questions, but they are what persist in my head after reading through this thread:
You say it's your gf who keeps not wanting you to move out. With the challenges she seems to have, why is that? What is she getting out of you living there? I worry that, with 4 kids, she's found someone to help with the house and kids, keep her company if she's at home during the day, etc.
My bf does not want it that way, he feels that becos of the love we have for each other he would find it too hard.
is a red flag to me. If I knew him I might be calling bullshit. I know there are closed triads, of course, but I find it interesting that in the current dynamics you and she seem to be sharing him more than anything. From what you've told us I get an impression of more a V with him at the hinge than a triad. This quote sounds pretty hypocritical to me, that you can be "brought in" to their relationship but can't have any relationships of your own outside of them.