There are several reasons why the smell of urine can change. Diet, medication, environment, illness, infection, etc.
When you were at the hospital, they used little pieces of paper to test for amniotic fluid. If that test showed the fluid was urine, its pretty right on. Are you noticing when you are leaking? As in when you stand, when you move, when you are sitting still, when baby moves, etc?
Also, you could have a urinary tract infection. That can make your urine small different.
Well if you already had it tested and they told you it was urine then it probably still is. Maybe you ate something that affeceted the smell of your urine or maybe you are dehydrated. Am. Fluid smells sweet and urine does not. If you are still worried then have them test you again!