I am definitely not a coach, but the thing that caught my eye the most was your first step. Your first step is different more times than not, you usually pause, but the pause is of different lengths and then there are a few times where there is no pause at all. My guess is this leads to ball reaction that can be quite different from ball to ball. I would try to eliminate that pause altogether.

I agree with what was said above.  The first step is going to be what helps you get the momentum.  In some cases, you paused and then in others, went right into the second step without hesitation.  That can affect your speed and it can ultimately affect the reaction or line you're playing.

I would work on the first step- find something that will be comfortable and work to make it a good habit.  If it were me, I would eliminate the pause but move into the second step in a nice, controlled way.  In fact, this is where having a coach or partner around to videotape you or give you feedback is a good thing.  Even if you're videoed on a cell phone, it still gives you visual feedback that will be valuable with working on this.

Not so much worried about the 1st step as I am the 2nd and 3rd. You have fast feet which causes you to muscle the ball throughout the swing. It results in inconsistency in shot making and unnecessary length from the ball leaving you 7 pins on good shots. I would slow down those steps and loosen that armswing. Allow the ball to freely flow back and forth with no muscle. You'll be amazed at how many shots you can repeat using a free armswing. Also, try not to grab the ball at the bottom. You're left handed, you dont have to. The ball on our side is a lot smoother off the backend because of the lack of track wear as is on th right side. Obviously, you want to play into that and allow the ball to read. Just my. 02 from watching your vid.

The first step is off to watch but if your use to it and can adjust the timing of the rest of your approach then it isn't really an issue. Timing is what is most important and consistency in what you do. There are many great players and pros that all vary in their styles and approaches but they are consistent and able to repeat shots along with other things that make them great. That comes from lots of practice as well as coaching.

For me it is your arm swing. It is a little short in the back swing and looks like your muscling the ball instead of being relaxed and letting the ball work for you. Doesn't mean you can't be great doing it, but it can be a source of inconstancy especially if fatigue becomes a factor.

What is it that your struggling with on the lanes when your bowling would be the better questions to start with?