How many cups is a standard size yogurt?

I don't think your question is clear. To my limited knowledge, Yogurt is not a straight protein like chicken or fish that you would measure in serving size. If that is the way you are supposed to measure it , and can receive 1/4-1/2 cup protein 3x a day. That means your total protein for the day is 3/4 to 1-1/2 cups total per day. Meaning you have up to 3/4 cups left for the day.

I typically eat the six ounces and feel fine.  I switched to greek yogurt - much more protein!  Have you tried it?

I went to your home page and couldn't tell if you have had weight loss surgery yet?  Have you?  If so, what kind and when?

Do you have a eating plan to follow?
Are you meeting with a dietician?

Yogurt has some protein and many fruited yogurts have added sugar.  Some yogurts are really more like sweets than nutritious protein sources.

What type of yogurt did you eat?

We can help you more if we have more details and history.