Once you dial in exercise mechanics you have to be able to repeat them. As with any skill in life or sports doing something well once doesn’t mean a whole lot. You need to be able to do it consistently the right way.
In a training program there are multiple ways to be consistent. During each session you need to be consistent in form for each repetition. Not just your reps, but even your rests should be consistent. Try to find the right amount of time to fully recover between sets of heavier lifts. Then only use a weight that you can handle with the mechanics you learned.
The consistency needed throughout your week and month is even more important though. Weekly consistency simply means getting in your workouts when they are scheduled. If you have great form and focus during each session, but only make it once a week you will never reach your goals. Skipping the step of consistency for volume or intensity may even push your goals further away. Working out super hard one day a week is not nearly as effective as doing something small 5 days a week.
In the end, the concept of consistency is a testament to your commitment. IF you truly want to reach the point you have affirmed is your goal then you will put in the effort needed to make each and every session on the calendar. The consistent work is what will get you there. You may not feel as motivated some days as you do others, but with your sincere drive to get where you want to be you will show up anyways doing each rep with the focus you understand is needed.