sorry if someone has already said this, but are you demand feeding or trying to follow BW's 3 (I think?) hour rule? Whilst this is an interesting observation, its not necessarily a 'one size fits all'..
I also read BW and liked bits of it but I found my son around this age, was a real guzzler towards late afternoon, early evening, with me feeding about every hour or so. I wonder if your baby is sucking your finger but might benefit from a milky suck?
I wonder if your baby is getting a bit overstimulated in the evening? do you take him back into the lounge if he won't settle? Perhaps try to start chilling out time - lower lights, not too much blary telly - a good hour or so before you want to aim for bedtime...?
Our breakthrough came when I started winding down (as in 'wind the bobbin up' - not 'getting wind up'!) with my son in the bedroom and gave him evening feeds when in subdued light, no tv on, gentle music (he seemed to rather like cat stevens...
)
Anyway the point is, after a few days of doing this, he really did seem to begin to understand sleep and bed was iminent.
Good luck, it will get better, promise