Wow - Karen, this is so beautiful! I SO love that you did this - and that you shared the experience and your deep questioning! I am sooo impressed. And you wrote this so well; I could feel all of it. I suppose it helps that I relate to everything you said.
I suppose in an ideal world, yes, you can only love another as much as you love yourself. However, it's not like there's a measurable system with this, where you can say, "Yay! I made it! I'm there! Whew! Took the final exam and now I love myself unconditionally! Now I'm gonna go and save the world!"
It's more about the process. And the more you are mindful of sending unconditionally loving thoughts to others, the more you will see your own wounds, the places where you need love or healing, too. Through the process of sending unconditional love when it's hard and you feel judgemental or angry, you are given the gift of remembering how it feels to be on the receiving end of judgement and anger when all you really want is to be loved.
This process is the best mirror. The more you practice being Love, the more you will come up against the places where you need to give it to yourself - with a hefty dose of forgiveness now and then.
The more you do this, the more loving you can be with yourself and with others, too.
And here's a tip. Instead of just focusing on envisioning compassion and empathy for that person when you feel judgemental etc., try looking past the behaviour. Remember that this person is wounded. This person is acting out those wounds. Behind those wounds there is a perfect spirit. Try to see that spirit - or at least imagine it, or understand that it's there. It's kind of like ignoring bad behaviour in a child, or ignoring someone who's being rude in public. Don't give it any attention; look beyond it and remember there's a light in there somewhere, there's a spirit trying to be seen but temporarily hidden by emotional wounds.
Maybe that will help.
You're doing such a great job!! And I'm so so so happy for you that you did this! Thank you so much for letting me know how it's going - and for the shoutout, too. I have so much respect for you and your work. I adore you!