First off i want to say i know how hard working on naps can be! Naps are the hardest to fix and unfortunately take the longest.
IMO - is it okay to use the paci when wakes (have a look at the thread at the top of this forum "wake to sleep" it should answer a lot of your questions on this tech. including how long it will take, when to pat and when to stop, etc.
I know a lot of mom's including myself decided to work on just 1 or 2 naps - cuz like i said, this is darn hard - not to mention carrying for all there other needs! So yes, i think it would be fine to work on just 2 out of 3.
I am feeling like a failure because he doesn't seem to be getting it.
Any mom who takes this much time to try to teach their LO sleep is not a failure, he is just learning and it will take time. So be more gentle on yourself and go out or visit or walk when you start to feel down.
I hope this helps! Don't hesitate to post again if you need support, that is what we are here for!