Add a little bit of beef base it will enhance the stock or a couple of the Knorr Vegetable Boullions.It sounds like you are looking for a bit more body to the flavors.It's also possible you just need some more salt,garlic? A little thyme is also good, another thing that is good in Brocolli Soup is a couple of drops or more of lemon juice and a pinch, a tiny pinch of nutmeg. Without the cream you just are not going to get that rich taste that comes with cream soups.
Dont forget you need a bit of black or white pepper.
If you dont like it real thick then cut back on the flour and butter roux then it wont be so thick and then you can add the cream.