So, Dragica was 16 when she gave birth to Vesna? If its in 1969 you should contact the municipality in Pancevo.

The phonebook lists a lot with the same surname in that region: http://www.11811.rs/BeleStrane/Pretraga/sve/sve/%20%20Pan%C4%8Devo%20(sva%20mesta)/pe%C5%A1i%C4%87/sve/1/0NO2FFKN

And 7 in Kacarevo: http://www.11811.rs/BeleStrane/Pretraga/sve/sve/Ka%C4%8Darevo-(Pan%C4%8Devo)/pe%C5%A1i%C4%87/sve/1/POAPHDAAD

Hi Sergej,
Yes, that is what I thought, thank you.
Pančevo
26101
Trg Kralja Petra 2-4
013/344 422

Official birth, marriage and death certificates can only be issued to direct descendants and only if requested in proper format via official request (in Serbian, with local administrative taxes and fee paid in advance). You must provide exact name, surname, place and date for the document you need issued.
However, ID number required (JMBG) means one has to have Serbian citizenship?
Therefore, I should probably hire Domovina Genealogy (Geneologija) to submit the request on my behalf?
Or, have I misunderstood?

Thank you for the telephone listings!
Melissa

Hi Melissa,

Yea, Serbian laws requires that. But, you could also write a letter and send it to the seven people listed in the phonebook. Serbia knows a lot of small communities and you might just find direct family. I dont have any experience with the agency you listed, but if you don't feel anything for the option I mentioned you could hire them.

Do you speak the language?

Hi Sergej,
Unfortunately, no — I have to translate for Serbian language.
I will keep your suggestion in mind.
The adoption papers specifically mentioned that my family was from Ivangrad, Montenegro.
Perhaps that is where I should focus my search. My mother was merely attending Belgrade university.
She may have returned to Montenegro afterward, or gone on elsewhere.
If she married, then likely she would be under another last name.
Thanks very much!

A lot of families migrated from Montengro, Dalmacija and Kosov into Vojvodina during that era.
Do you know of a family saint? Icons with e.g. Saint Nikola on there?
If it is Saint Nikola then you should go indeed to Ivangrad which is part of Berane. There is a lake there called Lake Pešić.
https://www.google.com/maps/place/Pe%C5%A1i%C4%87a+Lake/ @42.8541714,19.6797012,15.25z/data=!4m5!3m4!1s0x13529b0d450e2041:0xeceb3b19dab6b29!8m2!3d42.8554839!4d19.6888546