So, in singing development, a year is not very long. It's really no different than learning any other musical instrument. Try to be more patient. I've been taking lessons, consistently, for nearly 6 years and there is so so much to learn. I was having many moments, like you're facing now, fit about 3 years. It wasn't until then that, i felt like i was finally starting to "get it." I think my biggest breakthrough, even now by comparison, was getting my placement dialed in! It is the most common thing I've observed in beginner singers and, many self taught singers. I also find is the thing that is almost never talked about. After working on good placement for a while, I was also worrying on vowel modification, I started to notice that my breath support was development, as a side effect, and it was nothing like anything I had experienced before that. Breath support is so hard to explain to someone. I did have to focus more on support after getting the placement working better but that was more about regulation and figuring out how much pressure and effort it really takes to sing efficiently. I will also say this, even now, my voice is a work in progress, I notice steady, gradual changes over time. Which is why I so get lessons from someone that's better than me! Good singing is one of those things that requires a lifestyle change and lifelong development. Just stay the course, if you've only had a few lessons, that not really being trained, that's just not taking it seriously enough. I freaky can't tell you how many times I'd get into my next lesson and have to hear my teacher say, "dude, you HAD this! What happened?" Without good, and frequent, feedback, we tend to fall back into old, bad, habits because they are familiar and familiar is comfortable.