It sounds like you need to practice retrieving your boat. No disrespect. But since you've ran it dry twice, I think you need to relax, slow down and get a routine down for yourself.
Sometimes people can get anxious or pressured at the ramp. I'm not saying this your problem, but I've seen it happen. People rush, for whatever reason, and make mistakes.
We're here to help, so I hope you don't get offended.
When retrieving your boat...SLOWLY power toward the center of the trailer. Then when you're certain you are on your mark, shut down the engine and trim up your drive as you coast onto your trailer. If there's wind or current, compensate for that. It's all about knowing your boat and dealing with the elements around you. Practice and most of all repetition. Repetition is important because if you constantly perform a procedure the same way every time, you won't forget any of the steps.
On a side note...the depth of your trailer is very important too. Too deep and you'll float over your bunks/rollers. Too shallow and you'll be working hard cranking your winch.
