These things can't be diagnosed on the intraweb.. with a decent video, maybe. I've done private casting instruction for decades, taught Orvis 101 and 102 classes for 9 or 10 years, started off as a volunteer prior to working at Orvis.
Worked with Aaron Riemer, Mike Kinney and many others from the FFF. I'm actually going to start working, on my cast with Todd Sosmel of the FFF next year!
Casting and fishing are different, trying to diagnos your cast while fishing is tough. Practice your casting prior to your trip, whether its for a day, week or month! Golfers go to the driving range, prior to playing golf, particularily a new tough course or if you haven't been out in a while.
Hunters do the same, sighting in their rifle, shotgun, handgun or bow, black powder.. whatever..
While fly casting can feel like "riding a bike"! It really isn't. IMHO...
One of the main things I do as a casting instructor is to help my student learn how to diagnose their cast. Golf is the same, when you're out playing...
And watching your backcast, and the lift and the pulll of course, is VERY important if you want to become a better caster. While the fish don't give a crap about your backcast, timing, speed or whatever doesn't matter. The better you can cast, the better and more efficient cast you'll have.
Watching videos on YouTube or wherever is great, but only if you are watching someone who knows what they are doing.
Whether you choose a private lesson or six is up to you.. but I would recommend it.. with me, or someone close to you. Check your local fly shop, the FFF casting instructors or take videos of yourself and figure it out.
Just my 2 cents, after years of doing it.. actually more like Austin Powers... 1 million dollars! LOL!