All airlines are notoriously stingy about low-mileage redemptions in Biz or First. Don't blame yourself; as you say, you don't have much experience with this.

Do try Brussels; it's a less popular destination. Also Milan and Berlin. But you should probably get used to the idea that you won't be able to do this trip the way you were hoping. You'll have to move to coach, or change dates, or pay for J.