Hello Dragan! When I first saw Hummingbird hawkmoths here in Italy, I really thought they were tiny birds. After seeing your enquiry, I spent the afternoon looking for old photos (they have not come to our area for several years now).
There is also another hawkmoth which likes to hover over flowers, which I saw on a Sicilian island, that is more like where you were at Epirus.
nos. 1, 2, 3 Hummingbird Hawkmoth, Macroglossum stellatarum L. (forewing 1.6 - 2cm), Lunigiana Tuscany July 2013
nos. 4, 5 Striped Hawkmoth, Hyles lineata F. (forewing 3 - 4cm), Marettimo Sicily April 2018
The measurement the book gives is of one forewing, so two forewings + body width to get an idea of size. The second kind, Striped Hawkmoth, is quite big.
I am sure you will find better photos on the web! Hawkmoths are beautiful, some kinds with forewing of 6cm. You were lucky to have seen them in a wonderful setting.