Can I have a rhinoplasty right before I get pregnant?

Although your body will accumulate water weight and increased circulating blood volume in pregnancy, the results may be negligible compared to the amount of swelling that would occur if you would not become pregnant.  I would recommend completing the surgery and giving yourself 3 months as necessary prior to pregnancy.

It's true that the nose and face can swell with pregnancy, but it's not a lot, and you wouldn't even notice anything for a long time into the pregnancy. And the swelling wouldn't harm what was done in the rhinoplasty.
So, for example, you might have the rhinoplasty perhaps two months before you start trying to get pregnant, and that should be plenty of time.
Be sure to read the section in the "Learn more" link on how to stay out of trouble while searching for a rhinoplasty surgeon. You should only have surgery if you are able to make yourself very confident in your surgeon's skills. Read that page very carefully. 
Finally, I usually make computer morphs when I'm answering a RealSelf question, to show the changes that are possible for your nose with a rhinoplasty, but of course you didn't post any photos. At the *very* bottom of the "Learn more" page is a link to instructions on taking and sending photos that are comprehensive and useful for an online consultation like this, in case you'd like a more complete evaluation.

While it is possible to undergo a revision rhinoplasty before you get pregnant, it's more important to understand that you may need steroid shots to manage the poly beak deformity present over the next few months after the surgical procedure. You will not be able receive steroid shots if you're pregnant. Might be best to just wait till after your pregnancy to undergo a rhinoplasty revision.