Don't worry :) You're definitely not alone and LOTS of parents feel like this! Children push buttons in us that we just didn't know that we even had - I remember thinking I was a really patient person until I had DS 
One question - do you think your natural tendencies tend towards authoritative/strict, or permissive? Is it that you're trying to establish order but don't have many tools in your box other than shouting and threatening, or is it that you're trying really hard to be "nice" and trying everything but nothing is working and eventually you end up shouting and threatening because you feel out of control?
If you're not sure I'd say the first is likely if you often feel as though shouting is becoming more of a first resort than you mean it to and that you're being negative all the time, and the second is likely if you find that you swing wildly in a cycle of nice, nice, lovely, nice, kind, EXPLODE.
I ask because the way to stop/improve is different. I kept following all the advice for the first when I was the second, and it didn't work. And likewise if you're the first but follow advice for the second, it also won't work.
The first means you might want to look up some resources on gentle parenting or non-coercive parenting, to build a whole new set of tools which perhaps your mum might have found useful, as well. (We can only do the best with the information we have at the time.) There is a great book often recommended on MN called How To Talk So Kids Will Listen, which is definitely good, and also a website called Aha Parenting.
The second problem tends to occur when you have issues with boundaries, setting and upholding. This can happen as a backlash from a childhood which was too strict, but it can also just be a personality thing. So the way that you deal with that is to stop reading all of the gentle parenting websites, because those are advice for people who already know how to set boundaries, and instead learn about boundary setting, and in particular where to set a limit so that you're still totally in control when they cross it, and you don't feel panicky, rather than setting it right at the limit of what is acceptable so that as soon as they cross it there's already a problem. Something like 1, 2, 3, Magic is more useful here, though I'm not a huge fan of the book, it's good at teaching how to set boundaries.
For both issues I also really like a book called When Your Kids Push Your Buttons. :)