In Maine, Trulia is fed by the multple listing service (MLS) that all the agents use. I don't know which listing is yours, so I can't tell if the agent just let it feed from the MLS or they actually entered it on their own. Either way, you will have to contact your agent.
the following link goes directly to the MLS
search for your listing there - if the photo is wrong there, then it was fed from the MLS. If not, then the agent created the listing directly on Trulia. If the photos were fed from the MLS, you really want to get those changed because the MLS sends listings out to multiple websites, not just trulia..
the MLS allows up to 25 photos to be entered. Trulia will take all of those, plus if you create the listing directly on Trulia you can add as many additional photos as you want.