A lot of players told me it's hard to refuel without seeing the Probe infront of you.
IRL, Pilots have indicators either inside the cockpit (little crosshair or lighting), Or on the Tanker itself (usually an external lighting system) to help them line up.
If you focus on the Drogue or the Probe, you might set yourself into oscillations going up and down trying to catch it.
Instead you focus on keeping it steady, and use your indicators to line up.
I hope this helps you in any way :)