Hum. Let me adress ths points, but I will add the real question here.
- Is your work outstanding? Really good? Average? So - so?
The rest of the points depends on that question.
My age doesn't help
I really do not care about this, but the point related with age is experience; if your proposal really solves a comunication problem, a visual identity problem or just is a nice work.
Working for some years with an aplication does not make you a designer. I will post a rude example but the case could be similar. Working with wrenches and screwdriver does not make one an automobile designer. The program is just a tool.
I'm too kind
Nop, probably you are insecure, and probably you need more experience, and knowing the work you do gives real added value to the client.
I haven't developed a portfolio yet.
This is the first step. Do this and confront it with people and see if it has added value.
I do not really know if your prices are good or not, because I have not viewed your work.
Take a look at this: Why is it that people are so surprised that graphics design can be hard?
I have this graph:
Where the income is given by 2 variables.
The quality of your work, and the type of client you have.
The type of client is probably limited by your age right now, because probably a medium sized company will not hire someone your age. But again, the most important aspect is talent and problem solving work.