if your milk looks transparent/thin - it probably means that you have more foremilk (more sugar, more water). do you empty the breast when you express? the richer hindmilk (more fat, more creamy) only comes towards the mid/end of each expressing session. and it's needed to help baby last longer between each feed.
also the milk will have different creaminess throughout the day (usually creamier in the morning), and from day to day. so dont't worry too much.