I have this panel in my house and the main 2 switches say 100, like in the illustration. Do I have 100 amp service or 200 amp service panel? Thanks.

100 Amp. There are two hot legs, one pole per each leg, and each is protected by a 100 Amp circuit breaker.

There is also a label on the panel, usually on the inside of the door, that states "100 Amp".

A 200 Amp breaker will state "200".