Atleast for me!

I just got the game yesterday, and gotten a few games in so far, each ending with the same thing. I like to build planets up, then move to the next juicy one and tear it apart, and rebuild.
Though, about 30 minutes in in each game, the AI tosses theese fleets of 14-20 Siege armadas on me, and totally wipes out my planets before I can do anything about it.
In the last game I thought I'd make it, were expandin faster, had the pirates paid off to go after the AI's all the time, had two nice big fleets holding three choke planets with 6-12 gauss platforms, 3-6 hangars and one planet even had shields. Weps upgraded for most ships too, lmr's had the MIRV torps..
Then came the AI siege fleet, first it wiped out my most heavily defended planet with my biggest fleet attending defence, and warped out, I killed maybe 7 or so ships out of 24 (I think), 10-15 minutes later I see the armada coming again, one lane away, this time for my economic chokehold planet. Needless to say, I hit "quit"...
I've read on how to build defences, have a fleet etc, but you can't kill the Siege ships quicker than they can kill your planet if they come in theese numbers!
The sad thing is, if a regular fleet shows at heavily defended planets, like a huuuuuuge pirate raid, they get chewed to bits by the defences, but Siege ships just go for the planet, ignoring everything else and chews through shields and 6000 HP in a minute.
Perhaps one supposed to use the same tactic and just skip all the nice bits of the game because you can't defend against this ONE type of ship properly? I know I could probarly build my own siege armadas quicker than the AI, but then, one would miss like 95% of the ship content, not to mention building of planets and trade networks...
I'm enough flustered to just give it a rest, because, if there is no point against the AI's , it will be the same online... everyone will just spam siege ships.