More accurately, you screwed yourself, because the guy who hired you for 25% less than your market value didn't put a gun to your head.
You accepted the job willingly and you rationalized the choice. (for the record, a job at Google would probably bring 2x cash and would be an even better resume builder than a random startup).
At the same time, you should stop thinking that rewards correlate with value provided.
You think that you should get more money because you created a lot of value.
There is not answer to the question you asked ("how much you SHOULD get").
In business, this is governed by BATNA, Best Alternative to a Negotiated Offer.
To the person who hired you, BATNA is another gullible young programmer willing to work for less than he's worth.
Therefore he will not pay you more than he what he can pay someone else.
You, currently, have no BATNA. You don't have another offer so the deal you have is the best deal available to you.
Your best option is to learn from your mistake.
Start looking for a new job. Interview at 30 places. Collect offers. Either pick the best one or use the best offer you got to negotiate a better offer from other places that gave you offers (including your current job) (if they seem better to you).