His day seems to be quite long (14h), that may lead to OT. On the other hand his catnap is quite late and he might be not tired enough to go to bed. Is he waking from the catnap by himself?
I would consider resigning from catnap as he has two long naps and go for earlier BT. So if his 2h nap ends at 3:30 and he got up for the day at 6:30, I would try to put him down at 7:00-7:30 (depending on how tired he is). If you think he cannot cope until 7:00-7:30 (as it is a long awake time), I would try to APOP a catnap as early as possible (ie at 5:00-5:30) and cap it after 15min. Than aim for BT at 7:30.
If that doesn't work, and you cannot yet go on 2 naps but there is no time for catnap, you should cap his earlier naps (sic!) to still manage to do a catnap. We are currently doing that:/ - and I hate it but that's the only thing which works. Probably the best solution will be to cap his first nap at 40-45min mark, than make second nap after a slightly shorter A (15-30 min) and aim for 2h nap. And than you make a catnap but remember to cap it around 2-2,5h before BT so not to have a bedtime fight.
Regarding DF, that's easy. Around 10-11pm you sneak to his room and put a bottle in his mouth:). He should start eating:). When asleep! There are many problems which you may have, but give it a try and let's see what will happen!