“Real women are curvy”
Well, that’s outright body-shaming. You may compliment your curvy friends with this ‘compliment’, but what about your not-so-curvy friends? You shouldn’t really insult a body type in order to compliment another. You should just say “You look fantastic” or “Your outfit looks great on you”.
“You look great, but not really muscular”
Again, you should have stopped at “You look great”. You can’t expect everyone to be developing abs and biceps. Maybe they are trying really hard to do so, but you aren’t really appreciating their effort. You could just say “You’re looking great. What are you up to at the gym?”
“You look amazing even after having a kid”
New moms have a lot to deal with. Postpartum pain, dealing with a new baby, hormonal changes, and certainly, they shouldn’t have to deal with this insult. It may make them feel that their child has made their body fat. You should just not bring their new-born baby into it.