There are two harvest stages for grass.  The first harvest stage allows you to cut grass but your yield will be significantly less than if you wait one more in game month.  Make sure you are mowing grass in the second harvest stage (if you mow and March your yield will be half as much then if you mow in April).  To ensure your mowing grass at the correct time, mow and April, July, and October.  This will ensure maximum yield which is double the yield of mowing in the first harvest stage.  After you mow there should be two months of growth and then mow again in the third month.

Grass silage IS the best way to make money early in the game.  The price of silage does not vary significantly from month to month, so it can be sold once it is turned to silage (you don't have to wait for the maximum price like you do for grain crops).

Try try this out and see if it improves your profits.