Hello, soprano here, let me tell you this, being an alto is a blessing.. you seem to have acquired a gift of singing but are unsatisfied with the range and you can definitely improve on that though it takes A LOT of hard work, time, effort, and even money if you want to take classes.
It’s true that I love being a soprano but I fail to hit the low notes despite many attempts and exercises, though withing about five sessions my range increased to about 3 notes up an down. reaching a mezzo soprano won’t be difficult but the high A’s and C’s will take quite a bit of effort..
And being able to hit alto notes is definitely beautiful, I’ve always wanted to sing Tina Dico songs which require a fairly lower range.
Best of luck 
BTW, check out youtube for exercises etc.