I am 13 and a self harmer and depressed and bipolar (my parents know) but how do I maintain a relationship with God when I have all this guilt around all of this? I feel like I've turned my back on Him by doing and feeling this stuff but I need Him to help me through it even though I know it will take a while.
One thing I've learned with my various issues is learning more about them makes a huge difference. Learning more about what you contend with does a lot to help remove negative emotions. I'm sure you know some about your conditions but learn more.
Also know the difference between explanation and excuse. You can explain certain behaviors you may have, but that does not mean you get to make excuses to not try to be different or to do wrong things.
I, for example, struggled for a long time with various areas of my personality and felt as though I was strange. As I eventually learned more about my personality and some traits it has I saw that I was actually very similar to a lot of people.
I understood some of my negative behaviors, and by learning all this o felt less guilt and wasn't as hard on myself.
I also have depression (nearly 30 years) and anxiety (almost 15 years). So my patience is lower than many others because these conditions cause people to have lower patience levels. Knowing this I felt better that I have this struggle, but I don't use it as an excuse to be impatient.
So learn more than you already know. It can also be interesting learning how the mind works, the causes, etc... and could be fun as well.
I had a friend who struggled most of her life with bipolar as well. She had good periods and bad as she tried medications of all kinds and various treatments. Now shes a bodybuilder. She spends her days in the gym, eating healthy. She found a way to channel her energy into something more constructive.
She, too, was a cutter and much worse, before getting more evened out. So you aren't alone in your struggles.
I also knew a guy that had bipolar that was on and off his meds, started drinking and smoking pot. Now he has no license, no job, is in and out of the mental ward, is usually stumbling drunk before noon, lives alone and his own kids want nothing to do with him.
Whether you end up like my friend who's doing something good with her life, or a stumbling drunk, is entirely up to how you handle things. You can control that.