I found sleep school very helpful. Usually you have to call and go through an assessment questionnaire and they'll let you know if/when you can get in.
However, your day naps sound pretty good for a baby of your DS's age, as does the bedtime routine. It sounds like you're doing the right things.
I would think about trying to settle to sleep a little bit closer to the last nap (so earlier), as they tend to get tired more quickly later in the day. I wouldn't re-run the bedtime routine if your DS wakes after bedtime, but go in only if he starts to get upset and try to calm him down again without getting up. The usual suggestion for calming them down is patting their thighs and shushing, but that never worked for DS.
You could also try the MCH Line for suggestions.