Control the pressure of Hydrogen in a small container without the use of a pressure regulator
More like a suggestion than a solution. 

First, understand what you are trying to achieve.
You are generating hydrogen at some rate and storing it at high pressure. From your previous question I understand that the pressure of your stored $H_{2}$ is only a very general approximation.

Your objective is now to extract $H_{2}$ in a controlled way without using regulator. This sounds absurd.

My complaints:


I am very sure that you do not have a pressure gauge to measure the pressure of your $H_{2}$ container. This is a serious design flaw.
When you will try to extract $H_{2}$ the flow rate will be really high.


Now to the possible solution:


Incorporate atleast one dual valve regulator. This will take care of both issues mentioned above. You will be able to measure container pressure, and  regulate flow-rate. 


(But you do not want a such a regulator ! okay. What you can do is to get the smallest one possible and connect the regulator using 1/8 inch or 1/4 inch PTFE tubes and keep it separate. The regulator will then need to have custom input connector. It is not difficult to design one. Regulator to tube can be connected using all metal nut-ferrule connection which are safe upto 2000 psi or more. )

Well, your safety should be prime concern than the size of device I guess. In case oxygen leaks in and temperature at some local point is enough there is a chance of SERIOUS explosion amplified by the high pressure.

Some things about which I am concerned:


Do you evacuate the container before filling $H_{2}$ in ? If not, you are making a mixture of $H_{2}$ and $O_{2}$. Be careful !
The container of $H_{2}$ can handle high pressure or not. Have you tested it ? You can test it with $N_{2}$ or just air before using $H_{2}$.