There are many things that can screw up a sleep schedule. Here are some things that might help:

• No screens an hour before you want to sleep.
• Do very little in bed aside from sleeping. Avoid phones, reading, watching TV, etc. This helps build up a psychological association between bed and sleep.
• If you have the option, enforce your sleep schedule at other opportunities. Wake up at the same time regardless. Avoid naps. Only if you have this option though.
• Do some exercise a bit before bed. Maybe some light yoga. If this makes you sleepy right away, do it just before bed. If this energizes you at first, do it an hour or two before bed.
• Limit lights at night in general (use blackout blinds).
• Light in the morning. There are cheap SAD lamps that can mimic the sun and turn on automatically in the morning.
• Occasionally, as needed, have a melatonin an hour or two before bed. It will make you sleepy. If you have it too often, your body will adjust to needing it in order to fall asleep. Once every two weeks might be a good goal.
• Allow yourself two weeks to adjust to your attempted schedule. Your body will mess with you for a while even if you're doing everything well and even if it eventually works.

it's no silver bullet, but there are programmes that will colour shift your screens to red at a set time. The idea is to mimic sunsets, as bright blue lights have been shown to keep people awake longer. Pretty sure it's built into most Linux distros these days, and Windows has it hidden somewhere in its settings. I'm not quite as sure about phones, might be worth poking around internal settings or googling "your phone model + blue light filter"

I'm so bad at a sleep schedule, but I think it's a trauma/anxiety thing for me. I've done the all-nighter when I realized I wouldn't get to sleep on time.

I don't know how to improve a sleep routine and the guides I've seen were hard to stick to

i find chamomile tea helps, usually after sunset and/or an hour or so before I actually want to wrap up and go to bed

when i run out of chamomile, i just drink a mug of hot water.

Haha yeah, just woke up at 4 pm today

magnesium supplements induces verymild drowsiness and it helps with your magnesium levels.

It won’t put you out, but it helps a tiny bit without creating new problems (like melatonin, I’m dependent on it currently and it sucks.)