I'm not sure whether it helps, but possibly trying to enforce a routine at this stage would be helpful all round, if difficult to get going at the start.
Bath at around 6, quiet time getting ready is dim room, nice feed, into bed by 7pm. This is where you will probably have trouble, CC, PU/PD whatever method, but get them used to going to bed in the evenings at this time. I don't think 17 weeks is too young to expect this.
Still do your 11pm feed, and wake / dream feed as necc. Deal with nighttime wakings as you do.
If not awake by 7.30am, try rousing them by opening the crutains. Get them fed.
As to daytime sleeps - my two were difficult daytime sleepers. I managed better with DD2 working on the principal that babies need to sleep every two hours of awake time. Watching closely for those sleepy signs around 1.5 hours or 2 after waking, and as soon as you see rubbing eyes, yawns, etc - take to bed, feed, dummy, rock - whatever helps. No sleeping after 4.30 / 5pm means they should be ready for bed at 7pm.
I know it sounds easier in principal than practice, but if you persevere, you get your evenings back, and hopefully a better rested baby in the long term.