PP's estimate of $20 per meal for tips is a good estimate--some may be less, but it's better to over-estimate that. From your original post it sounds like you have that covered already.
Since you're not drinking alcohol, that "strictly spending money" would go towards additional food not on your DDP and souvenirs.
By the way, do you mean DDP=
Disney dining plan or Deluxe dining plan? I see it both ways on these boards...
My comments are assuming you're on the regular dining plan--if you're on Deluxe then you'll not need to spend any extra money on food!
Will you & your bf want to order appetizers at table-service meals? Will you want to eat extra snacks or get an extra QS meal some days? You'll be at Epcot during Food & Wine and may end up making some extra food purchases there--or you may save your DP snack credits for Epcot and then pay cash for other snacks at other times. I know you won't really know till you do it, but think about what's likely, based on how you guys eat in the real world. My DH & I would probably end up spending an extra $20 a day on extra or F&W snacks, as well as on the occasional appetizer.
Your souvenir budget also depends on what you guys are likely to do & want there. Personally, I buy almost nothing in terms of souvenirs--generally I get a nice photo album and one magnet. My husband gets a shirt and the kids can pick out a stuffed animal or toy and a shirt or inexpensive (ha!) sweatshirt, and they can spend their own money on whatever they want. However, my sister and her family go to Disney and spend, spend, spend on shirts and cups and pins and toys and stuffed animals and clothes for stuffed animals and figurines and swords and...well, you get the picture. My family budget for souvenirs is far less than her family budget. (To be fair, I spend my money staying at Deluxe resorts, so Disney gets our money one way or another!)
I recommend setting your daily budget for your trip and doing your best to stick to it. If you have $1000 to spend over 2 weeks, that gives you about $70 per day, which includes extra food and souvenirs. With no alcohol getting purchased and a pre-paid dining plan, I think you should be okay--you could eat some extra snacks or an occasional QS meal or appetizer and still have $50 per day to spend on Disney junk...I mean, souvenirs. (Truthfully, it's not all junk--many souvenirs are very nice--but I just don't need more stuff in my house!)