All builds listed are calculated under the assumption that you want maximum crossbow accuracy, which is a must in my opinion. That's because level 35 does not allow you to move exceptionally fast and your own team might outrun you when you reload, so you are left behind and die. The only way out is camping a faraway point and hitting targets over the distance, and to do that you need max accuracy. Besides, you can't effectively counter archers unless your accuracy corresponds to your crossbow's maximal potential.
The bad news first: If you want your current armor set, the shield, and the heavy crossbow, the end result sucks. This build moves too slowly, and the 1h wpf is obviously too low:
Level 35 (7 999 021 xp)
Strength: 15
Agility: 27
Skills to attributes: 4
Ironflesh: 5
Power Strike: 5
Shield: 4
Athletics: 9
Weapon Master: 9
One Handed: 23
Crossbow: 195
A reasonable suggestion would be to replace the Heavy Crossbow with a default Crossbow. Here is the build:
Level 35 (7 999 021 xp)
Strength: 12
Agility: 30
Skills to attributes: 4
Ironflesh: 4
Power Strike: 4
Shield: 4
Athletics: 10
Weapon Master: 10
One Handed: 121
Crossbow: 183
I checked if it's an option to remove shield but keep the Heavy Crossbow. I don't recommend it, because it's low IF and the 1h WPF is too low again:
Level 35 (7 999 021 xp)
Strength: 15
Agility: 30
Skills to attributes: 10
Ironflesh: 1
Power Strike: 5
Athletics: 10
Weapon Master: 10
One Handed: 15
Crossbow: 209
Here is with default Crossbow without shield. It's roughly on par with the second option.
Level 35 (7 999 021 xp)
Strength: 15
Agility: 30
Skills to attributes: 10
Ironflesh: 1
Power Strike: 5
Athletics: 10
Weapon Master: 10
One Handed: 108
Crossbow: 189
Summary: I recommend using #2 or #4 for now. Consider going higher level. If that's not an option, reduce your armor weight drastically, so #1 and #3 become viable with lower xbow wpf and higher movement speed and 1h wpf while still achieving maximum accuracy.
Sorry, that's as good as it gets for now.