You won't get above 11 on game day without being in the cup (and the cup is over... but I have heard people claim to get to 12 on game day when out of the cup but haven't actually done it myself).
Playing normal does not reduce your enthusiasm but it won't increase it. Your enthusiasm always slow reverts back towards five no matter what effort level you play at. If I had to take a wild guess I would say that if you were at 11 on Saturday and played normal you'd probably fall to 9 (maybe 8 but probably not lower) by game time on Tuesday, but this is me just sort of guessing based on my previous experiences.