Is it normal for the nose tip to be bigger at 5 months after rhinoplasty?

It's still too soon to tell what your final results will be. You need to have patience with your body as it begins to heal. The skin, bone and cartilage are all traumatized during surgery. Inflammation (swelling) is the normal response and will help your nose to heal and look beautiful in the end. If, one year from now, you are unhappy with your nose, then that is the time to think about a revision procedure. Right now, concentrate on other things you like to do and let your nose take its time to heal. I hope this helps.

Tip swelling is very unusual after a closed rhinoplasty. In an open rhinoplasty it can take up to 12 months for the tip to settle down but swelling for this period is unusual after a closed procedure. I would return to your surgeon for assessment and advice. 

It is typical to have swelling after rhinoplasty that can last 6-12 months.  This can fluctuate and be worse certain days than others or certain times within the day.  Often the tip of the nose holds onto swelling the longest.  Try to be patient as you are still reasonably early in the healing process.