Really impressive work. Obviously you're quite advanced, so I'll just give some of my personal impressions. Here are a few quick opinions/ observations:
-Good buffa affect
-solid themes, classical idioms, attention to detail (harmony, voice leading, etc.), overall very strong work. What is your background in terms of education and experience?
-in the opening, I'd want mm.13-18 to be more of a half-cadence then a modulation to V, and then mm.36-44 have a stronger confirmation of the new key, usually accomplished by standing on the dominant for a few measures. As is, it is too abrupt harmonically, and rhythmically to read well right off the bat.
-sudden third relation after the general pause at the beginning of development section totally out of the blue and unprepared. Unconvincing. Similarly the coda thing at m.277, m.281, etc., is also a strange, IMO.
-the moment of arrival of the recapitulation in Haydn, Mozart, and Beethoven was a significant dramatic moment, and the lead-up was almost always low-energy, a kind of generalized anacrusis. The recapitulation is the new start. You have a build-up, which puts it at the middle of something (I noticed the same in your symphony)
-retransition too cadential. The transition in a classical sonata has a 'destabilizing' function, and the retransition, consequently, also must do the same, but by some sleight of hand, instead take us back home. It is a double subversion. If you just write a cadence formula, you might as well just stop the piece right there.