Hi. I'm having a rough time with the website, as I'm sure others are experiencing, so bare with me. I will certainly check into any post and try to offer help. I'm no "seasoned pro," but with the wealth of knowledge on these boards I'm sure we can find answers for you. First off, you are doing great. If he will take that long of naps even some days, it's a great success. Just like us, babies are going to have changes every day, especially at his age. I find that it's haywire for lack of a better word at the moment up to 3-4 months when you might see longer stretches of similar patterns, a few changes, a steady stretch, and so on. At his age, you are doing just what you should to help him learn to sleep. As I know you've read the book, as parents we have to teach sleep and not expect them to just know what to do. The BW community does not recommend leaving baby to cry for any length of time. However, if you feel yourself getting frustrated, you should step away momentarily to regain your composure and try again. It sounds like, though, that you are absolutely on the right track. It can take quite a while for baby to catch on, but the more reassurance you give him, the better off he'll be feeling so comfortable that mom is right there for him.
When his nap lengths vary, just adjust your routine as best you can. The most important thing about BWing is to read your baby's cues and thus respect his needs (meaning don't feed a crying baby if he's crying b/c he's tired). By having a routine, you'll be able to anticipate his needs and you'll both feel more secure and comfortable.
Keep up the great work and I'll look for future posts.