Given you're a young person, unless you have had something that would create issues with those muscles -- like a recent vaginal birth -- it is highly unlikely you need to work on those. It's also very unlikely that's why you're not experiencing pleasure or orgasm. It sounds pretty clear to me this isn't physiological.
What it sounds like *to me* is like you probably are experiencing orgasm: that shaking sure sounds like it, but that because the lead-up to it isn't something you are finding very satisfying or pleasurable, even when orgasm happens, you still feel unsatisfied. Orgasm, all by itself, isn't usually what leaves people feeling satisfied, but it's also a lot harder for it to feel that great when what got us there wasn't even more exciting and satisfying. When we aren't that excited in our heads but reach orgasm anyway, that's when we most often experience very mild orgasms that just don't really deliver. Understand what I mean?
If toys excite you, then for sure, some toys might be good: if you have access, you may want to start with something like a better vibrator than an electric toothbrush, pair that with something that gets you very mentally turned on -- like some kind of fantasy -- and see if that leads you anywhere. It just sounds to me like the mental piece may actually be what's missing most here. If you don't feel very excited while any kind of sex is happening, it usually just won't feel that satisfying if and when orgasm happens.
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