Hey there,
Firstly, i'll just say that I never thought i'd be replying to a post of this nature on a site such as this. Ha.
I too have a sebaceous cyst (on the inside of my right cheek) and I too am of similar age. I'm 22.
I first noticed the lump about 4 years ago and it never really worried me too much but now I notice it all the time. Similar to what you were saying, other people don't really notice it, until I point it out to them, or they catch it in a certain light or something. It has grown at a slow rate over that period of time, i'm certain of it - although I did lose quite a bit of weight recently and it may be more prominent now, as a result.
I saw my local doctor when I first noticed it about 4 years ago and without an ultra sound he diagnosed it as a sebaceous cyst and said I had nothing to worry about and it shouldn't grown too much more. I thought "meh" and kept on living my life, as I mainly wanted the opinion of a professional to confirm it wasn't anything serious.
I have grown extremely self conscious of it, to the extent that I avoid conversation, try and face people on the opposite side and try and rest my hand/arm over it whenever practicable (so I don't look like a complete idiot).
I've been back to a different doctor in the last 6 months, who referred me to a skin surgeon type doctor. He said it was too large to do under a local anaesthetic and he wouldn't want to risk nerve damage, especially on the face. So i'm now on the public waiting list for elective surgery (i'm in Australia) which could take anywhere up to 18 months.
I don't know the point of this reply, or what i'm hoping to get out of this. It's really good just to type to someone experiencing a similar issue. I suppose I was just having a bad moment and googled 'sebaceous cyst' looking for more info and possibly a painless home remedy that may remove or subside it.
Does the castor oil work, or have you found anything that does?
Thanks and hey, I know what you're going/have gone through.
Alex :-)