Well, first off, looking @ your avatar you're doing FINE!
Your front delts look nice and proportioned - Seems like maybe your middles are the ones you want more bulk with?
|I'm still learning what works with delts, but it seems to me they're VERY sensitive to the angle at which I work them. Example - I like Arnold presses as my mainstay movement. I've been doing them seated for years. Recently, I tried doing them seated, but with just a bit of recline on an adjustable incline bench. - Like I was sitting in a normal chair, instead of a straight backed one. Felt Like I hadn't worked 'em in weeks the next day!
Same with reverse pec-dec- flies. I just started standing up and leaning my head against the pad - instead of sitting. It changed the angle just a bit and wham, I'd swear I saw new development in two workouts.