I tried to update my phone and lost photos from the last 6 months, how can I get those back?

restore them from the latest backup

I'll assume that you imported them to the computer for safe keeping, like you would pictures from any digital camera. If so, then you can sync them back to the iPhone, if you did not perform a backup as stated in Templeton's post.

Are you trying to tell us that in 6 months you NEVER uploaded your photos from your phone to your computer?