No, from what you say, a drink pkg is not needed.
Get a coffee card (with 15 punches) if you like Starbucks crafted coffees (Tall sizes are included, Anything larger or iced 2 punches). Or use the diamond lounge coffee machine. Water bottles, you can pick up from Diamond Lounge (no voucher required) / any bar on your D vouchers loaded on your card or order a water package. Drinks and soda, between you and DH you can make use of your diamond vouchers. From what you are describing of your drinking habit, you really do not need to buy a drinks package.
These are thoughts from some one who struggles to use 5 D plus vouchers a day on non alcoholic drinks, waters, you name it. I do get water pkg 24 bottles or depending on the length of the cruise and coffee card since I love cappucinos. At times the water pkg has left overs if the D plus lounge and vouchers have sufficed. Save the $ on the package and get a nice massage at the Spa on board. JMHO.