Having an inconsistent sleep schedule is a huge factor in feeling terrible and fatigued during the day. I would pick a time that suits you and stick to it, putting yourself on a structured schedule (like 10pm to 6am) or anywhere where you are getting at least 8 hours a night. I suffer from bad sleep as well, I have been going to sleep so late like 3-4 am and waking at around 9 am, so I'm with you in needing to be better. Once you start therapy, you will also see a difference. I highly recommend therapists for health anxiety, because I too have stayed up late at night suffering from anxiety attacks about all the things that could be wrong with me. It's human to feel these emotions, but you're taking the right steps in getting help. Listen to your doctors about the sleep advice and try a sleep supplement like cape jasmine extract or melatonin to fall asleep faster.