I couldn't say I have DS2 in any set routine, but he sleeps through approx 11-12hrs overnight and tends to only have 2 x day sleeps of between 45mins-1hr. Occasionally he turns into a grizzle grump around 6pm, and if that happens I just put him to bed and then give him a dreamfeed (BF) just before I go to bed. He'll still sleep through till approx 6.30am-ish.

Would it be possible to gradually string the times of your DS's naps out a bit if he's content to stay awake a little longer? Say, 9.30-10am, then 1.30-2pm. Might help get him to 7pm, if that's what you're hoping.

From memory, DS1 was down to two sleeps around this age too. I agree with the others about resettling - if I can get DS2 back to sleep around that 40-odd-minute wakeup, he will sleep up to 2 hours. Generally though, once he's awake he's bright-eyed and bushy-tailed!