As promised i did some Research
& still i dont think it is authentic
I dont know the store the Seller mentioned but i know that there are Many Many fakes in Bulgaria , Romania, Slowakiq, poland....
All your mentioned concerns are obvious & well Not right on that bag.
I ve Never Handled this bag in Real live
I can only Look at the hallmarks & your mentioned ones & the leather Patch d&G is bothering me ( just Fyi D&G is the cheaper more affordable line of Dolce & Gabbana

. )
If you really want to keep that bag i Would recommend you a 3 rd Party authentificaton. Contact Caroldiva ,mypopette & ASK them if they do Dolce & Gabbana.
As far as i know Dolce is Not so Common & pretty tough
I m Sorry that i cant help you more. Good Luck sweetie.