I do not see how anxiety over not having enough money is self-sabotage. True, worry-induced anxiety is, worrying does not "do" anything for us, is always about the future which we cannot know or do anything about so merely draining but if one doesn't have "enough" money, supporting one's self is tough!
We can control some of what we do; if we need to quit a job for our mental health, we get another job
first and then quit, not just quit and worry about where the next job/money is coming from? Some of the examples you gave were like that but it is very very hard to even think straight when you have 10 things to think about and only 8 resources! I was just working on Christmas gifts, only using 2 catalogs but trying to mix and match and figure out people and costs was a couple-hour job and I had to quit for the day instead of even thinking about going online and trying to order/get addresses to send things to, right!
I find doing something, even something small like making lists, helps me move forward with less stress. That you wait until the last moment to do school work; that can be one's style and if it works for you, the "energy" from last minute work like that is not bad. Just recognizing that is what you do, can get rid of some of the stress; you do get the work done, who cares "when" as long as you turn it in and get the marks you would like? If you do not get good marks or turn it in late, that's a different problem.
I think it is great that you are thinking about all this and getting to know what it is you do and how you feel like/dislike it. It all depends on how you feel about what you do. If you don't like how you do something, you figure out how to change your habits; just because we were taught something as we were growing up does not mean we have to keep them. Yes, habits formed early might take a bit longer to change because we have been performing them for longer in that way but all our behavior is under our control and can be changed if we want to work on it.
The only stress/anxiety/worry I do not like for myself now is when I am awake at night and so I have started "doing" something about the things that worry me then. Yesterday I spent the day working on my finances and budgeting and today I feel good and excited about what I did and there are a lot of scary worries that cannot exist anymore because I took the time to address them yesterday.
That you made bad decisions in the past, should remain in the past. You can learn from those decisions and that's the only way we do learn! You cannot learn much from when things go well because there's not much to remember. That's why we remember the bad dreams and memories; what you did on Tuesday, September 24, 2002 in school, probably does not jump out at you?

That's because it was an "average" or "good" day at school. I remember learning to "divide" in math because the day when I started 4th grade (the year in my school system where we would learn to divide) we were given a math test and a new girl from another school system was sitting next to me and we were horrified that there were multiplication (just started in 3rd grade) and division problems and she did not know how to multiply and I did not know how to divide and we taught each other in about 2 minutes before the test

Think of the detail you remember from when you worked on a problem or made a mistake and want to remember the mistake so you don't make it again (buying a bad car from "a guy"). That's a little bit why it is good that they give fines/tickets for DUI, so you "remember" and don't do it again.
So, sort out the stress that "helps" you and reframe the mistakes so you learn/remember something positive from them and make a few lists on current problems you want to address and make some plans on how to address them?