So I came to the party late, but here are four useful tips. If it is just upstream but not pushy, just keep doing what you are doing and sideslip or ferry to the bottoms of eddies or the insides of curves to catch the slowest part of the current. Being able to go in a tight straight line helps you stay close to shore, or in the slower water that often extends much farther downstrean than you think. Train the eye to see the speed. Second, if it is getting tougher, try to pole on the side that you are least likely to spin out down stream. That is, if the current is stronger to your left, then pole on the right. If you start to swing to the left, the solution is to push the stern quickly to to left to align with the current again. So pole on the side that you would prefer to hug. Third, if it gets really tough for a short stretch, do a "quick jab" stroke until you get back to a slower current. If you don't know this or the name, you hold both of your offside hand at chin level and the onside hand maybe 8" below it. Now you do quick crunch/squat plants and recover by standing back up and dragging the pole forward though the water. Don't release your hands, just one two three, four five... It is a sprint to get you through a tough spot that you can't avoid and will get you huffing, but it is an old tried and true technique. Again, pole on the side away from the stronger current and you can incorporate a stern pry off the gunnel to align the boat again if it is swinging away. Fourth, my home urban river is a bedrock bottom with some stuff on it, but a record flood washed everything downstream and now I can't find grip for most of my practice length. This is often true below chutes and really pushy bits everywhere. If you can get a good solid pole plant then use every last inch of it before you have to reset. So push, then climb hand over hand to the very top and give a really hard quick push off the end to give you a bit more time to find the next anchored plant. If the bottom sucks and the pole wants to skip off, then set the pole end down under control and don't just drop it like normal. Also set it at a higher angle than normal, so that more of the force is downward rather than backward. Obviously I think about this. Good luck!
Good advice.