Concerning alien presence in the universe, shall I explore further?
IMHO, yes.
Just to compare your game to the one I'm running now:
known star systems, all modifiers as normal, 30% NPR creation for me, 20% for NPR, 20% minor races, only Precursors and Rakhas active, 20% Ruins.
After 90 years in the game, there are: 177 systems, 114 grav surveyed ones, much less geo, and I met: 1 Rakhas, 1 ruin outpost (discovered in the last year, so I still have to investigate it), 1 alien race in 4 systems (links between them are still undiscovered) with 2 confirmed populations until now (distances from Sol at 16.4, 16.6, 26.6 and 31.9 in real space).
The Galaxy is almost empty, up to now, but I feel it rather realistic in this way.