Hey and welcome! This sounds exactly like lucid dreaming. A lucid dream is only a dream in which you're aware of the fact that you're dreaming. You seem to have had these dreams quite a while and learned some very nice dream control. Dream control can be tricky though, but it's connected to one big thing, belief. If you believe you can't do something then you most likely can't. On the other hand if you're entirely sure you can do something then you most likely can. However, dreams does not always bend to ones will no matter how much you believe. We learn how reality works and the older we get, the more used to the physical laws we get. We know what is possible and what is not. To let this go you can tweak the control a bit, use the scenario or scene to your advantage. This is called "passive control" and is very easy. Expect things to be around the corner or behind you instead of making them appear infront of your eyes. Summon a great sports car if you want a vehicle whilst on a racing track instead of a lion.

What happens when you get lucid is absolutely normal. The brain doesn't really seem to like that we're lucid in dreams and the risk of waking up once you get lucid is alot higher than in a normal dream. First of all this is because you pay too much attention on the fact that you're sleeping in bed. We have all the normal senses in a lucid that we do in real life. If you stick to the senses in a dream and ignore your body in bed you'll stay in it longer. Mindset is also very important and you can't have thoughts like: "I hope I don't wake up soon" because that'll just wake you up. Try to go with the flow and casually rub your hands or focus your eyesight whenever the dream starts to get blurry, then you'll have longer dreams.

What you do when you jump back into a dream is called: "Dream Exit Induced Lucid Dream" aka DEILD. It's very useful if you're lucid and the dream is about to end prematurely and there's no way of saving the dream. Just lie completely still and go back into the dream by visualizing and ignoring the Sleep Paralysis you'll most likely feel.

To get more of them, choose a technique and practice it. I suggest you do what you've already done and perhaps throw some mantras in there for extra effort. The main techniques are MILD, DILD and WILD. DEILD is a form of WILD.

Good luck!