I’ve been living with one kidney all my life, what are the possible complications that can happen?

I have been told I have blood in my urine and that back in January started this really long episode of depression that leaves me very tired and anxious every day, and I have a pretty awkwardly round face. 

You can live happily with a sole kidney for life without any complications if you are lucky.  My sole kidney caused no problems for over 60 years until a long term unrelated illness and high blood pressure got in the way.   So basically watch your blood pressure, eat healthily (avoiding salt and too much protein)and drink plenty of water.  Of course, the blood in your urine should be investigated and treated accordingly.  If you are not under a urologist and a renal consultant then do ask for referral to have this thoroughly investigated.  What is your present eGFR (kidney function) at present?

Unfortunately, I don’t know. I only recently got a refferral to a urologist as I’ve only recently seen my GP for the first time in my life (I’m a teenager) and all he said was that I have borderline high triglyceride and LDL cholesterol levels. 

You need to ask what your eGFR is.  As far as your triglyceride and LDL levels are concerned, as they are just borderline, you may just need a little tweak in your diet and exercise programme to improve levels.  Look up foods that are recommended to improve HDL levels such as avocados and oily fish.  A good HDL will offset/reduce the risks of having a borderline LDL.  Meanwhile, I hope the urologist can get to the bottom of the blood in your urine - if not an infection it may just be something as simple as a polyp in the bladder.  Good luck!