First off, FYI, 0.25 lbs of frozen raspberries is pretty negligable. The general rule of thumb is 1-1.25 lbs per gallon to get an appreciable raspberry taste.
As for the sweetness, your beer is likely dry because you are currently mashing too low or losing too much temp during your mash.
I would personally just mash high, and make sure you are holding mash temps within AT LEAST 3 degrees of the starting mash temp. Adding grains that are not in the original recipe can easily throw the whole recipe out of wack.
Without changing the grain bill at all, you can mash in the 156-158F range, activating alpha amylase enzymes that will leave some longer chain sugars in the final beer that yeast can't eat, so there will be a residual sweetness in your beer.
Also make sure you are doing a 10 minute 168-170F mashout following the mash to lock in the mash profile.
That's how it's done. Let me know if you need any further explination of those techniques!
Good luck!