Oh hon don't worry. You figure out pretty fast what they want and don't want and how to make them happy. Every mother (well the good ones anyway) worry about whether or not they'll be a good one. Especially before their first child.
relax - take a deep breath and realise that there is not such thing as a perfect mom- do your best the more you stress your baby will read your emotions and REFLECT them - if you are upset you baby will be too!