Hard to say, as you've not completed your timeline - please do, as then your stats contribute to the quoted times, and it helps others going forwards. 1.5 years is possible if your I-130 is approved fairly soon, a lot depends on how quickly you do things at the NVC stage. If you're ready to go, submit your docs, pay your fees, etc, then it may well be late spring rather than summer.
On the plus side, Stockholm is super quick, only 1 or 2 months wait for an interview letter - other countries are 2 years or more just for that stage.