Hi Perplexed - when playing via steam I think the key to take screenshots is F12 so try that - give us a look at how you set up your games and then an empire of yours say 30/40 years in.
You really shouldn't be getting annexed in 20 years on a single AI game with no Fallen Empires, but make sure you turn off clustered starts just in case.
On normal difficulty just doing normal things (expending steadily, researching core techs, building space ports, keeping fleet at or near the fleet cap) you really shouldn't have much difficulty at least getting to the end game crisis...
You really shouldn't be getting annexed in 20 years on a single AI game with no Fallen Empires, but make sure you turn off clustered starts just in case.
On normal difficulty just doing normal things (expending steadily, researching core techs, building space ports, keeping fleet at or near the fleet cap) you really shouldn't have much difficulty at least getting to the end game crisis...