I don't know if I will be much help, but at least I can say, I feel your pain! my 4-month-old was a short napper for what felt like a long while. though we had a routine of EAS (now sometimes EAEAS), we weren't (and still aren't) necessarily on a 4-hour routine. I tried w2s, but had no success.
now, she takes a 3-3.5 hour nap in the morning after a short awake time. I think we were keeping her awake too long. I have read that sometimes the first awake time is shorter because the first nap is kind of a continuation of night (and will often be longer), so baby is often tired earlier. it doesn't look like your awake times are too long, but does she show tired signs when you put her down (very quiet, less active, yawning, rubbing eyes, maybe fussy)?
then she takes either one more long nap (and sometimes a short cat nap) or two shorter naps. but that long nap in the morning is SO wonderful!
besides letting her sleep as long as she wants for her naps (instead of waking her after 2 hours), we also are letting her fall asleep on her own in her crib. sometimes she will protest cry, but somehow it has helped her sleep better, I think. sometimes after she wakes from a short nap (when it should be a long nap), we will let her "cry" for 5-10 minutes. sometimes she will put her back to sleep. of course, if it's an all out CRY cry, we will get her, but often it's kind of a whiney cry, which usually means she will go back to sleep. I had to stop rushing to her whenever she made noise!
people always told me that they will grow out of short naps around 5-6 months, too, so maybe that will be of comfort to you!
your LO is so precious!!
best of luck!
--tara