Ok, I need some tips on timing DD's day sleeps better.

At the moment she is up at 7am and then seems tired by 8am, so I put her to bed and she generally sleeps for 2 hours. Then its catnapville the rest of the day, with up to 4 x 40 min naps until bedtime at 7pm.

The problem is, that by 6pm she is soooo overtired because the catnaps just seem to take the edge off. At the moment she can only really be awake for about 1 hr and a half, before needing another sleep. She self settles and can resettle well, so I am assuming I am putting her to nap too early? Like she is not tired enough to have a proper sleep?

It is awfully tedious to be constantly getting her to sleep in the day, so how do I try and consolidate the catnaps into a better afternoon sleep?