Hello there, you did the right thing in reaching out.
It is common in our youth to go and go and go until we crash out from exhaustion; it becomes a habit and even a lifestyle, but once we start getting older, we discover that go-go-go is very bad for a sleep schedule.
The word "schedule" is apt. You have to stop letting sleep be about exhaustion more about resting. Therefore, treat sleep more as a ritual, and you'll find that getting into a decent sleeping schedule is much easier.
Look at your upcoming day, if you have to be up at any particular time, trace back 8-10 hours and designate that your bedtime. Once you've done this, make your bedroom more conducive to rest, make it a restful environment; take out any noise-makers, anything that could be used to distract you or keep you awake. (In my bedroom, all that I have is my bed and my dresser for my clothes!)
When you get to within two hours of your bedtime, don't eat anything else. You can have a non-stimulating drink, but no sodas, nothing containing caffeine. Take a good, long, relaxing shower or bath, if you elect to take a bath, supplement it with some epsom salts and a soothing scented candle. Don't vigorously scrub yourself, just take a relaxing soak. Hot water relaxes muscles and helps calm the nerves.
Once you start treating your rest like rest, you'll find the transition to sleep much easier. A good, relaxing sleep schedule can even help to alleviate nightmares and night-terrors.
As far as your disturbing sleep imagery is concerned, the only solution is to stop avoiding it, just go to sleep and let the bad dreams happen. Your mind sorts out your day's experiences through dreaming, and whatever your mind is running when you rest is something you need to think about and process. Bad dreams happen, but you can't let an unsettling dream chase you from your bed. The more you confront your night-time demons, you'll find that they return less.
Additionally, there are several medical conditions that can result in sleep disturbance. It may be prudent to consult your primary healthcare physician.
Good luck and rest easy. Always remember that you matter, and you are not alone.