You are definitely in the right place.
The timing out after inactivity serves a few purposes. One of main reasons for it is so that the Binder federation is not paying for resources not being actively used.
I think at present it is about ten minutes.
There is a safety net in place is you are using a typical launch to get you back quickly to where you left off. See Getting your notebook after your Binder has stopped.
It’s one of those things you want to test before you need it. That should let you recover much more smoothly than you may be doing now.
If you are using JupyterLab, the interface will look different; however, the corresponding buttons will be there.
A couple of things could be causing that. It may just be traffic is busy and so resources are tied up. Sometimes that particular site has too many people hitting it. I think there is a limit of 100 concurrent users per source repository.
And always make sure you are using a launch URL that begins https://mybinder.org/v2/.... You cannot reconnect to an old session which sometimes confuses users because they try just pasting the URL of the page they had been on. You need to go back to where you launched from originally.
I know one Bokeh tutorial can be launched from this badge below:
The direct launch URL for that is:
https://mybinder.org/v2/gh/bokeh/bokeh-notebooks/master?filepath=tutorial%2F00%20-%20Introduction%20and%20Setup.ipynb