Blowing nose 3 months post rhinoplasty.

At 3 months it should be safe to blow your nose.  All incision should be well healed and you should not damage anything.  Again, you should do it with minimal/moderate force.  

Thank you very much for enquire.

Swelling after a rhinoplasty depends of the surgery complexity.
In this regard, the nasal swelling Post-op It can last from two weeks to two months.
To reduce this swelling, I recommend you perform delicates daily lymphatic drainage massage therapy over the face (around the nose) avoid sun exposure, and take pain/inflamation pills, as your surgeron precribe you.
Kind regards, 
Dr. Emmanuel Mallol Cotes.-  

Being 3 months removed from surgery, you should be fine to blow your nose. I generally clear my patients to begin light nose blowing at one week following surgery, and full nasal blowing several weeks down the road. As always, though, when in doubt contact your surgeon for clearance on issues like this.

Since your chosen operative surgeon knows you best I would return for follow up in person to address this question.