Here is a hint - try the progression with this (/D = means D in bass , etc)
Fflat major/Fflat, Bflat major/D, G flat major/G flat, C maj/G nat, A flat major/A flat, Fflat major/A flat, E flat major/G. This is all in E flat with a chromatic ascent. I know you have a different bass line but this may help you better understand the opening is not atonal, rather you allude to E flat minor and its relative major G flat major before settling on E flat major.
This is along the lines of what your teacher is talking about. Review your whole piece in this context of E flat major, its parallel minor E flat minor and the relative major of E flat minor - G flat major.