Amy-
I have a couple of thoughts here - not sure which ones might strike home?
1: It looks like he's on a 3/3.5 hr eating routine right now. Have you tried pushing back his feedings some toward the 4 hr mark? (He's 4.5 mo, correct?) My LO started going closer to 4 hrs btwn feedings a little before she was 4 mo. When you do this, you may need to offer him MORE food at each feeding. I BF, so I'm not exactly sure what amount would be appropriate? Maybe try one oz more per feeding?
2: Have you tried starting his day a little earlier than 9? 9 is pretty late to begin the day - maybe wake him by 7:30 or 8 for his first meal and go from there. We currently do about a 12 hr day and a 12 hr night (wake around 7, bed around 7) - that seems to be a common goal for this age.
3: I hate to mess with his A times b/c it looks like he's napping well, but his A times look very short (1:30 & 1:15 for the first 2 A's) for his age. The goal at this age would be 1:45-2 hrs awake. My LO has a hard time making it to 2 hrs w/o becoming OT, but I try to push her gently in that direction.
4: This could be a GS? My LO just had one - it is common to have one around 4 mos. She'd been STTN, but started waking.
5: Is he teething at all? Sometimes that can cause NW's at this age?
6: Have you tried offering MORE than 3 oz at the DF? Just curious if he'd maybe take a bit more then.
I know, lots to consider... like a recipe for disaster?!

Let me know if any of that helps - Tara