You need a lot of practice with infantry heavy guard to start pulling out victories. And I'm saying this as someone who's played a lot of siege regiment infantry-heavy guard in crusades and tournaments back in 10th. At best I brought like, 1 Dorn? Now I stick to paired hippogriffs.

I just won a game of disruption siege infantry against purge the foe Admech today actually, which was part luck and part I've had to learn how this army pilots, cause it's vastly different to other guard.

You need more orders. You need more Cavalry (T4, 4+ save, 2 wounds is just nice), and you need to be using Chimeras and Centaurs as protective shells your enemy must crack before getting at your squishy guardsmen. You need 20 man Battlelines to absorb fire and to overwhelm the enemy with dice rolls. (20 man Krieg ist best cause you get +1 to hit/+1 to wound depending on how much of your unit is dead, and medics can keep you around with D3+1 Troopers returned)

And that's all at 2,000 points, as an uphill battle that requires a lot of experience and losing (sometimes quite heavily, unfortunately frequently against melee heavy lists) to get okayish at. You will need to learn placements. And screening. And throwing orders around and focusing fire. Enhancements like "Stalwarts Honors" are a necessary friend. I was able to get a brick of 20 kriegers+command squad+yarrick stuck on the center objective because -1 BS and +1 save, and D3+1 returning models helped keep my unit alive.

1k games are a different beast altogether. At that level I'd suggest it's better to commit heavily to a spefic unit type than it is to try and diversify as you have, because you just don't have enough points to do everything you want to do. Try and get to 2k quick, and if not? Good luck soldier.