Your bf should make sure you ALWAYS have large quantities of goodies on hand.
There should be a wide variety of goodies.
There should be plenty of fattening ones, and lots of liquid calories--milkshakes are particularly good. (Sodas are very fattening but really unhealthy, I'd avoid those).
Don't try to force yourself to the point of being completely stuffed (unless, on occasion, you feel like it). Instead just get into the habit of snacking frequently.
You may not gain much at first, but keep it up.
Your boyfriend should keep tabs on which goodies disappear the quickest, and make sure to replace them quickly, especially the more fattening ones.
Your boyfriend should monitor your gain and praise and reward you for each new pound, each new inch. Rewards may include your preferred sexual favors.
And of course, the gluttony pledge may help:
fantasyfeeder.com/cms/forum/viewthread.php