Temper flare-ups. is that usually a bipolar sign?

It can be.: Temper flare ups can result from a variety of causes. To find out if you have a diagnosable disorder, you should see your doctor.

There must be more: Yes, people with bipolar often have a very short fuse. But the diagnosis is based on many additional (and more weighty factors). If you are concerned enough to ask here, it's worth seeing a pro. Early intervention can make an enormous difference as multiplied over the years.