Have you started to worry about your parents?

[Kralizec]

Uhm, what?

Roman Empire - slavery
Medieval Europe - feudalism
Industrial Europe - limited democracy
Modern Europe - democracy

I fail to see where I got things wrong?

Here's where you got things wrong:

Serdom is for practical purposes a form of slavery. The word is derived from servii, a word which (if I recall correctly) the Romans used for both slaves (property) and actual serfs (men who were supposedly free, but tied to their "employer" by various legal barriers). Even they knew that in practice the two didn't differ much in practice.

Besides, even though the middle ages was not quite as bad as is sometimes thought, it certainly was a step down from the Roman empire during its golden age. To be fair; it could be argued that Europe was already slipping into the dark ages when the western Roman empire still existed in name.