I agree with you that this sounds Russian, or generally Ruthenian. But Polish has also a diminutive word "maluszku!" or "maluśki, maluśka" - if this is what "Mollyoshka" supposes to approximate. But I have no idea what "shootie" may mean.
Maluśki, maluśki, maluśki kieby renkawicka - from a Polish Highlanders Carol
This is a long shot. Using Polish transliteration: "Szczo ty maluśka?", or "Szo ty maluśka?". This would literally mean "What you little one" (speaking to a girl). "Szczo" or "szo" would indicate either Ukrainian or Russian language, definitely not Polish.
There is however a Polish equivalent expression - "Co ty malutka". It is hard to explain its meaning, so I'll give some examples:
Co ty malutka, nie bój się, nikt nie zobaczy!
Co ty malutka, ja jestem niegroźny!
Ej, no co ty malutka, jakoś to będzie!
In all three examples there are some sexual or patronizing overtones. But it does not have to be read this way if the girl is actually a little one. It may be a sort of invitation to further conversation or a game.