I need help, I've seen things in my past for which I cannot unsee.

I witnessed domestic abuse: 4-5 years old
I was sexually abused: 6 years old
I witnessed someone die: 10 years old

More than halve of my family have disowned me; My own Dad told me I was a mistake (first ever time I contacted him Via Instagram) he then blocked me, not spoking too since.

My moods change in ways I can only describe as a wave like motion, some days I am really happy and some days I am really depressed. But there's always a peak to both contrasts and overtime it changes. Sometimes I feel both very happy and very sad.
When I am very happy I am quite hyper and quite optimistic, however, when I am quite sad I am the complete opposite - I feel suicidal (I have thought of methods by my preferred method cannot be done in the UK due to the laws with the Helium production), I self harm, I have alot of bad thoughts that scare me most of the time I have a vivid thought of hurting myself usually at work when I have a knife (I always have thoughts of cutting myself, slitting my throat or accidents happening and I fall over on a knife.)

I self harm, I don't cut myself it's too messy, I burn myself. Primarily by my Cigarettes.

I have noticed that lately I have been hearing people mumbling throughout the house, even when I am home alone. It is kinda scaring me and making me somewhat paranoid because I am starting to not feel real with what I am hearing, seeing and feeling.
I also get into realistic scenarios in my mind where what I am imagining it feels like that I am in it as my body. (This has happened when I was walking down a street yesterday, I was imagining of a scenario of me, my girlfriend and my friends having a social gathering and I felt like what I was seeing was what I was imagining, I only got out of the scenario of when I almost got hit by a car crossing the street and they beeped their horn.)

Is there anyone who could think of what I could have? I have been referred to a psychiatrist but that takes a long time.