I feel a strange fluttering in my chest and just sometimes. could this be atrial fibrillation?

Yes: You can feel your pulse to see if it's irregular during an episode. Sometimes what is called an event monitor can be placed to capture the heart's rhythm and have it analyzed by a cardiologist. You should have this evaluated since intermittent atrial fibrillation can lead to stroke and other serious problems.

Possibly yes: However, there are many other types of arrhythmias that could cause the same symptoms. Also, fluttering in the chest may not be even due to an arrhythmia. Go see a doctor.