don't worry about having trouble with defending against bombards, we all have troubles with them from time to time =)
Bombards have an extremely long reload time (30 seconds), so you need to find some way to kill them while they are recharging. Of course you don't want to get destroyed by their "alpha strike" so I'd suggest placing a lot of cheap units right near the wormhole and hope they will take the hit. Fighters are a good choice for example. If you really can't spare any of your weakest fleet units, build a lot of cheap turrets. Building lots of tractor and gravitational turrets is also a good idea. You don't want those bombards to scatter around.
Just make sure that nothing of value is near when they arrive. Let them waste their shots and then destroy them.
I'm not playing with bombards in my current game, so I'm not entirely sure, but I do believe bombards can shoot at forcefields. You could have been just very lucky, so be careful.
Also, make sure all the waves only come from a single wormhole (by destroying warp gates), one that you can defend well. Having your command station near the wormhole can have it's advantages, but I wouldn't risk it against bombards.
Hope this is at least a bit helpful. Good luck =)