Is this enough for a change in custody?

Your daughter is of the age now that she can legally choose where she wants to live. Have her go the courts and tell them that she would rather live with you full time and visit with her father on weekends. (if that is what she wants)

There is nothing in here that would cause your ex husband to loose custodial custody. Joint custody only means that one parent is allowed to have the child live with them "the custodial parents" and the other is involved in the childs school, doctors, life, etc. The 14 year old is however old enough to talk to a judge and request to live with mom. Your ex has the right to move, have a life and live with whomever he chooses as long as the girlfriend isn't abusive to the daughter then there is no fault there.

Honestly not really. I have seen parents become homeless and that is not enough to change custody. There is such a thing as affidavit of Perference and your daughters opinions on who she wishes to reside with are taken into consideration but despite the myth unless the parents agree to it mutual and just file a formal change in court the child doesn't actually get to "choose" who they live with.

And to change a custody agreement to something not mutually agreed upon is really not likely. You have to show overwhelming evidence as to why the parent is no longer fit to have child on same terms. And I have seen case where homelessness, domestic violence, criminal conviction still don't make the parent unfit.

At 14 a judge is likely to defer to the wishes of your daughter in deciding where she wants to live, the instability is an aggravating factor against him, between that and her choice, I'm sure you won't have a problem.

At 14 she should be able to decide who she wants to live with. But he is entitled to visitation.