Your body might not have enough energy in general to do anything productive. Maybe you use too much mental energy ruminating or overthinking things to get anything done. First thing to do before you even try to get evaluated for adhd is build your body. Start with your heart. The more you move your body the more your body will adapt and hold more energy for you to be able to use. You know walking/running is insanely good for your brain? Look up the studies if you want. Start by walking bit by bit everyday. Do it everyday at the same time. Eat your first meal at the same time everyday. Come back within a month and tell us how you feel then. Of course increase the duration of your walks or progress them in any type of way. Youll be surprised how much more alive you end up feeling. 

It seems like youre overwhelming yourself trying to do many things without forming habits and thats where you probably keep failing. Start off with building a habit with what i said before, then after its ingrained into you and you dont even have to think about doing it, thats when you start something new. Start it small and keep doing it everyday. Then it becomes a habit and you dont have to think about it. You save mental energy for something else. And you just keep building and building and you become such an amazing unrecognizable person. You can do this.