How much is too much?

Me and my two friends drank. I am relatively new to drinking, have had like 10 drinking get-togethers in last 6 months. We both drank almost 170ml of 42% vodka. I have difficulty walking with my feet on a straight line like a field sobriety test, but they seem very better. They experienced drinkers. My question is was that too much? Or did they have higher tolerance since they ate seasoned drinkers?