Sorry, this is long, but I feel it will include information to help!
I have learned a few things about how to conquer this. I am inspired to try all of these things to help me as well. I haven't been diagnosed with Delayed, but I have diagnosed myself because the definition of it is what I have been living. Right now I am on disability that I don't want to be on forever, but no matter if I have a full time job or I don't. I cannot seem to fall asleep or even WANT to fall asleep at a normal 10-11pm hour. I just feel better mentally at night, and going to sleep doesn't sound fun because I just wake up early and do it all over again and I'm wide awake. so no matter if I get up at 7 am for work, I'm STILL not tired at a normal sleep time in order to get up for the am. So I stay up late and wake up early, so I'm a zombie every day. When I don't work, I find myself staying up until 6-7 am and sleeping until 2 or 3 pm, sometimes later. I'm desperate to change this so I talked with a psychiatrist and read up and this is what I have found.
The next thing you can do in conjunction with light therapy is take melatonin. Unfortunately, I am unsure the correct milligrams you are supposed to start with, so you can consult your doctor for his recommendation or just start out by using the lowest mg that they sell at the store or wherever. You can bump it up if you feel the lower dose isn't helping but again, I would consult with your doctor. I'm sure you've heard of melatonin right? It helps with the timing of our circadian rhythms ( our 24 internal clock) and our sleep. You can get it over the counter. The plan would be to take this dose daily in the early evening, HOURS before you aimed bedtime. So you do not want to take it right before you want to go to sleep. It takes awhile to do its thing. So there is daily light therapy plus nightly doses of melatonin to help adjust your brain and your sleep schedule. you can find all over Amazon.com and you have to get one that has 10,000 Lux, which is apparently the light strength, I'm not sure. And use it every day in the AM or midday for 30 mins -45 mins. I know you said you don't get up until 2-3 pm so I know that would be an issue for you to do lamp therapy in later morning or midday, so I would just do it as soon as you woke up and if things get better, you can start doing it earlier and earlier.
The next thing you can do in conjunction with light therapy is take melatonin. Unfortunately, I am unsure the correct milligrams you are supposed to start with, so you can consult your doctor for his recommendation or just start out by using the lowest mg that they sell at the store or wherever. You can bump it up if you feel the lower dose isn't helping but again, I would consult with your doctor. I'm sure you've heard of melatonin right? It helps with the timing of our circadian rhythms ( our 24 internal clock) and our sleep. You can get it over the counter. The plan would be to take this dose daily in the early evening, HOURS before your aimed bedtime. So you do not want to take it right before you want to go to sleep. It takes awhile to do its thing. So there is daily light therapy plus nightly doses of melatonin to help adjust your brain and your sleep schedule.
I also just read an article, a study or some write-up from some doctors on what to do for treatment for Delayed and he suggests Chronotherapy "which aims to restore the proper circadian pattern of the sleep-wake cycle through adequate sleep hygiene, timed light exposure ( light therapy lamp), and the use of chronobiotic medications, such as melatonin, that affect the output phase of circadian rhythms, thus controlling the clock." In this article he suggests several different things, which includes Light Therapy lamp and melotonin but he posted a sleep schedule that one can follow that can help you adjust as you go. I will post the link to this article and this schedule is posted in TABLE III. I'm kind of confused on some of the timings he is posting about, but maybe it would make more sense to you. He was saying that the schedule for when you start trying to induct the sleep schedule should be:
One-week induction phase Stay up the whole night on Wednesday Bedtime schedules are as follows. Thursday 6 AM to 3 AM, Friday 9 AM to 5 AM, Saturday 12 noon to 8 AM, Sunday 3 AM to 12 midnight, Monday 6 AM to 2 AM, Tuesday and thereafter 9 AM to,6 AM. Stay in bed between 8 5 and 9 h
But for example when he says "Thursday 6 am to 3 am" is he saying stay asleep for that long or stay up until that late? I'm confused. I want to understand this sleep schedule because I feel it would help adjust the way I sleep in addition to the light therapy and the melatonin. I would definitely ask your doctor about it. I can't believe he diagnosed you but didn't offer a treatment plan?
Anyway, if you are not confident with doing a weird sleeping schedule to help with this, I would at least start off with the light lamp therapy and the melatonin. Oh, and here is the link to that article I was talking about. Read all the Tables because it has great info on treatment ideas and plans but the whole article is informative as well.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3181779/
Sorry, this is so long but I hope it helps! I know the pain behind having this awful sleep disorder. It affects everything and I feel like I am tired all the time. Good luck!