Going to be a bit of a long reply, so I apologize in advance.
I can't relate to the whole custody situation so I have no business offering anything there. The most I can say is to continue fighting. Sounds like it will be hell but sometimes our worst battles make us stronger and something to think back on to remember how powerful we can truly be. As the above poster has said, you can always decide to CTB later if all else fails and you can no longer continue to fight.
On the subject of finding a significant other, there are some options. You can try to pursue the original guy you were attracted to and attempt to mend things together there or you can accept what has happened and move on. You never know, there may be a much better person you are attracted to that is equipped to love you and your daughter to the fullest.
There are options to meet others such as in events around your area, there is also the online dating route, it is just important to be mindful of who you decide to meet up with, some people can also be pretty trolling... from what I hear, on the female side.
I know it is awkward coming from a single guy but I actually know I CAN find someone, I am confident in my looks but sadly I lose interest way too quickly because right now, my mind is stuck on other things dealing with my intestinal disease and my current situation.
Bear in mind, you are 18. As I said above, there is plenty of time for you to still meet the right guy or girl, as for the now, you seem to be facing tough issues with custody and I personally feel that should be your main priority but I can't also tell you how to live your life.
I can relate to the lonely feeling of wanting a signficant other all too well but I can assure you, you learn to cope and accept it.
Also, off topic, I am sickened how they treat the Natives. Even here in the states. No one realizes just how much shit you have to deal with. In 2019, you would think racism is over...