I was hoping for some advice please.

Ive been playing for a reasonable while, 3 + years. Ive figured though that despite the fact that I understand and can use basic scales and know how to improvise (albeit not all that well), Ive never properly learned a full song.

I decided to go back to the roots and learn some songs on my acoustic. I dont have an electric at my disposal at the moment. Ive come to realise whilst learning songs which revolve around basic chord patterns/progressions (eg. you and me by Lifehouse, nothing at all by Ronan Keating, Wonderwall by Oasis) my work, albeit not wrong, sounds sloppy and not tight. I listen to the way people play some of these songs on youtube and I can imitate them without a great deal of difficulty but my playing just doesnt sound as nice.

Muting whilst changing chords is something I find to be an issue (or at least fully drown out the chord that was just finished), for instance, I found this problem whilst learning a horse with no name by America.

My strumming I feel sounds particularly ordinary with open chords, its not that I cant play these songs but that they just dont sound with as much feeling and tightness as I would like (as Im sure you can gather, I really strive for perfection).

My strumming in general though feels a bit haphazard and not smooth and clean sounding. I thought using a thinner pick may help and it has a bit but I suspect that this has something to do with my technique or bad habits ive picked up (I am predominantly self taught).

My apologies for this very extensive post. This isnt really the easiest thing to explain or even understand but I would really appreciate any advice people could give me on how I could improve.
Might I be a dick and suggest you get a guitar teacher, even for a few lessons, to examine your technique?