I am sorry to hear about your problem with Lucky.
My name is Rebecca. I am a veterinarian, and will do my best to help.
This is a tough problem. In older cats, I would look for things like hyperthyroidism, but that would be very rare in a cat this young.
What is your response to her yowling, if any?
One thing to try would be to give her 3 to 6 mg melatonin at bedtime, to encourage her to sleep at night.
It is important not to respond to her yowling in any way: don't get up and go to her, don't feed her ( or she will learn if she yowls long and hard and loud enough you will eventually feed her), don't even talk to her or yell ( and I know how frustrating it is not to yell! I had a cat like this).
I hope you can see what I am writing! I am not seeing responses from you.
I will try connecting with you in another format if I do not hear from you soon.
Thanks, ***** ***** need to get these melatonin tablets at the vet?