When Libby went through her nippy phase, I would blow in her face HARD whenever she bit. She did not like this and usually would stop. If the behaviour escalated (she would start making angry sounds and biting harder), I would seize her and hold her down near the floor. Not to hurt her at all, and I'm not sure why I did it. I'd hold her there for 30 seconds or so and when I'd bring her back up to me she would be calm and not bitey. IF she was still in a biting mood after that, I would conclude that she is simply not in the mood to be with me and would put her in her cage.
Either she grew out of it, or it worked, because she no longer bites.
So don't despair, things will get better. He is just trying to be the boss of you and he does not respect you, although he probably does like you. When my coworker brought her lovebird over for me to baby, I found him to be VERY nippy - as in, draws blood several times a day. Sometimes he would do this from the top of his cage or from my shoulder, where he would go so he could bite me without being batted off. I would press my back up against the wall (with him on my shoulder, not squished between the wall and my back), and rotate, which forced him onto the front of my shoulder. Then I would grab him and hold him down near the floor as I did with Libby. Or I put him in his cage. By the end of the week he was with me he was far less nippy.
Don't let him win. Don't let him get away with a single bite. Either respond by shaking him or tilting your arm, blow in his face, hold him down near the floor, or put him back in the cage (in that order if he keeps biting).
If you get frustrated, put him back in his cage. Work on constructive activities with him - teach him tricks, eat with him, play with foraging toys with him. Keep his mind busy so he develops confidence in you as a leader, and so he has better things to think about than biting. Reward his good behaviour with lots of praise and treats (first praise, then treat).
Put a sleep cage in your bedroom to establish a flock mentality.
You will get there!