So, this piece is in composite ternary form, because each of the sections seems to have two inner parts.
The first part of the A section consists of two phrase groups--the first phrase ends in an authentic cadence in the key of G, and the second ends on a B major chord. the next part of the A section begins after the double bar, back in the key of G. This section feels also like a phrase group--there isn't a period feel to it, especially since the harmonic motion doesn't exactly allow it. this section does end in a PAC, however, so the complete A section is simple, closed binary form.
The B section has a rounded binary feel. the piece dabbles in the key of d minor, and begins with two phrases ending in perfect authentic cadences. again, it never feels like a period to me--this part of the piece is almost too relaxed for such structure. this section also plays with the original melody in a new key, so it feels rather developmental.
The A section returns around measure 73 to round out the piece--only the melody is played an 8ve up and is not repeated. and then there's some weird extension at the end! like this: "blah!"