We had to put our LO onto a 4 hour easy before she could handle the 4 hour awake times. She was about 15 weeks aswell at the time. We had a lot of EASAEASAEAS... but her awake times have adjusted since then and after a while we had a good 4 hour EASY going.
I was also worried that she would not eat any more when I pushed her feeds back, but things greatly imporved. If they don't improve, then you can always switch back, and your LO is not going to suffer. When thinking of changing your EASY routine, it is always a time of watching your LOs cues and adjusting to meet their needs... it takes some work, but is really worth it in the end.
Good luck!