I can't throw Roundhouse kicks?

I can't throw Roundhouse kicks or low or high kicks, but can teep or some others, I just don't understand the concept or I don't know how to implement the technique, I researched hard and it stated that first the leading leg outward (in my case, left leg), and put weight and pivot. At this point everything is understandable but even I try to throw my body, hips, and legs Aming shins, that shit is pretty fucked up for me. So is there any tip or better explanation?

PS: I don't have a Coach, Gym etc. I'm all self-taught, I practice the move again and again till I understand the principal, I mostly shadow box to imply it, and recently I got a Punching bag but to my surprise I didn't have the material to fill it up so in also trying that too. (The reason I don't have any Coach, Gym etc is that there simply isn't in my city or near by, ik my problem buy need some help in that case).