To be honest it's a personal preference! For you, it might be too much when the makeup feels heavy on your skin or like your skin can't breathe (even if it looks really good). If someone is not used to wearing makeup, they could put on a light tinted moisturizer and it might feel like too much.
Here are a few signs that may help!
You can barely move your face.
You have lipstick smeared across your face.
You have very obvious contour lines.
Your eyelashes look spidery.
Your shirt collars are stained with makeup, etc, etc...
Other signs can show after makeup is applied and washed off for the day! such as discoloration in the skin, acne in unusual places, some swelling, itching, or irritated areas on the face.