Yes. My observations:
1. ADHD often comes along with depression and anxiety, because kids want to behave but can't control themselves in the moment. You really, really have to set them up to succeed -- e.g., look for distractions before they lose it, find ways for them to be helpful that, conveniently, keep them busy (even if it's sweeping the floor), help them find ways to feel like they are contributing. And be gentle when they fail -- jumping on them just triggers the anxiety and sense of helplessness. Catching them doing something right is infinitely more effective then negative consequences. They are not being bad on purpose -- they really, truly can't help themselves. The best parents/teachers figure out ways to convert that boundless energy into helping (one of my daughter's teachers, for ex., had her take the attendance list to the office every day -- it helped my kid get the wiggles out, and puffed her up and made her feel like she was trusted with this important job, which then helped her attitude for the rest of the day).
2. Read "Your Spirited Child" and "1-2-3 Magic." The former got me through ages 2-5, the latter helped me navigate 5-on. The key takeaway is they desperately need you to be their unshakable rock when they are flying off into outer space -- they need to know you love them and will be there for them and will not be moved, period. The image of the horsefly and the horse in 1-2-3 Magic still sticks with me -- the point is that if the kid sees that she is getting you mad, that makes her feel insecure, because she is this tiny little thing, and so if you are so week as to be shaken by her, she has nothing solid to cling to. You need to be calm and loving but absolutely implacable; she needs to know what the consequences of her actions will be with complete certainly, and she needs to face those consequences every single time, and you need to be calm and loving through the whole thing, and when it's done, it's done.
3. ADHD is the classic "two steps forward, one step back" -- just when you think they are making progress, they do the same dumb-ass thing all over again, and you want to tear your hear out. To maintain your own sanity, you need to look at things measured over years so you can see the progress.
4. Please see specialists and therapists. There are different meds, there are therapies like neurofeedback and the like, and there are just people with expertise who can help you develop routines and consistency and parenting skills that your kid needs you to have. It is tremendously challenging, but you can get through this and end up with a wonderful, interesting kid.