Yes, your body temperature is normal. A study of 150 people about your age confirmed that the average highest temperature any time during the day never reached 98.6° F. In fact, the average temperature at 4 p.m. was found to be a full degree lower at 97.6° F. This was very similar to your readings.
In the morning, their average body temperature was even lower, 97.3° F. This is also a normal finding. In general, body temperature tends to be lower in the morning and rises as the day goes on.
Im glad you know your own temperature. Its important. When someones body temperature is low to begin with, an increase may not reach fever levels. For children and active young adults, doctors usually define fever at 100.4° F or higher. But that assumes a body temperature of about 98.6° F.
Older people can be quite ill even though they dont seem to be running a fever. For example, an oral temperature of 99.4° F for you could be a fever because of your lower baseline body temperature. In addition, the fever response weakens with age. So the body temperatures of older people may not increase all that much when they are ill.
The flip side is that doctors need to be on the lookout for temperatures below about 95° F, especially in older patients. A low body temperature can be a sign of illness too. And its often not noticed by the patient.