You've gotten some excellent experience (I shy away from describing anything people say here as "advice"), especially from @Thas, and I agree absolutely with what was said: experiment and find what works best for you. Don't get hung up on labels and what works for others, rather take ideas and try them and see what happens. However, one thing you said I feel I need to respond to:
You aren't a failure at all: you are asking questions here to try to better manage your diabetes and get healthier. That makes you a success! The only kinds of "failure" that occur in diabetes management, in my opinion, are when medical professionals fail to properly diagnose and educate patients and when some diabetics "give up" and decide not to manage their condition at all. The former (medical incompetence) is entirely unacceptable; the latter ("diacide") is terribly unfortunate and sad, but completely understandable. Managing diabetes (of any kind) on a daily basis is really difficult and time-consuming for most of us, and some people just give up. One of the reasons why we do what we do here is to try to help people so that they don't give up and label themselves "failures."
So, on to my point. I would hazard to say that no actual diabetic really manages their diabetes, for the long run, with "good diets." It's always more complicated than that! Genetics, amount of exercise, the details of disease progression (sometimes fast, sometimes slow), and the emotional and social support we get from family, medical professionals, and other diabetics all matter enormously. If you read the stories of the "old timers" on this and other forums, you'll hear a common thread: "I started to manage my diabetes with diet and exercise after diagnosis, and it worked great for years (or months or even decades), and then it wasn't working so well anymore; now I'm on insulin (or other meds or a combination), and I have great (or acceptable) control again even though I had a period of time where I didn't."
This is just my opinion, but I'm going to state it anyways: if one is an actual diabetic (Type 1, Type 2, MODY, MIDD, physical, or any other disorder characterized by insulin deficiency or critical insulin resistance), and one lives long enough, there will come a time when "diet and exercise" is no longer sufficient to maintain healthy glucose metabolism. That is what being a diabetic means: we have compromised glucose metabolism. Every type of diabetes (with MIDD and Type 1 b being possible exceptions) are progressive, so far as medical science has shown. This means that, on average, the longer someone has the disease the more likely they are to experience reduced beta cell function or total beta cell failure. There are, of course, exceptions. If I manage to get hit by a bus before I see an endocrinologist, I may go into the books as a "Type 1 who successfully controlled their blood glucose with oral medication, diet, and exercise alone."
That would be a really poor description of both me and my disease, but it could be technically correct (if only because my GP won't prescribe insulin and I haven't yet seen my endo, who is dragging her heels because my BG management is "near-normal"). My ability to control my BG with diet and exercise (and Metformin) won't stay static through time: I have LADA, and it is almost certain that I will eventually have much reduced capacity to make sufficient insulin even on a no-carb diet; if I were Type 2 (my original diagnosis, as with many of us), that is likely still very much the case.
tl;dr: Being on medication, whether that be orals or insulin therapy, does not make one a failure in any sense. Diabetes is a progressive disease, and what you're doing today to manage it may not work next week or next year; adjustments in treatment must be made through time. Also, Your Diabetes May Vary: what works for me, or @Thas, or the rest of us here, won't necessarily work for you in the same way.
P.S. All that being said, eating low-carb will probably make your life quite a bit easier on the daily management of blood glucose front, although it is difficult for some (many) people to maintain such a diet in the long term. If you have weight issues, truly committing to a low-carb diet and some exercise is like magic for losing weight! Check out www.reddit.com/r/keto if you need evidence for this. Eating low-carb also reduces the amount of insulin you either need to inject or have your beta cells produce, so it is reasonable to expect that minimizing insulin needs will indeed prolong the life of your beta cell function. Then again, injecting insulin has also been shown to help prolong beta-cell function in both LADA and Type 2. Ultimately, you'll have to make a decision about what the best way to treat your diabetes is; remember that what you decide today won't necessarily be the best way to treat your diabetes next year or in five. And that is OK, not a sign of failure.