1pj The long morning sleep she is having is probably putting her off the rest of her sleeps. If you want her to sleep more during the day, I would wake her, for her day sleeps, after 2.5hrs of sleep. Definately leave the night sleeps. Though IMO, her long night & that long morning sleep would more than likely be enough. I would imagine that if they sleep long stints like that, their sleep is actually of a higher quality.

I always woke DS so he was feeding no longer than 4 hourly during the day but would leave him to sleep throughout the night.

Are you trying to re settle her after her day naps? Maybe she would sleep longer with a bit of re settling, If that's what you want her to do of course. Keep in mind that they have a 45 minute sleep cycle. DS always needed to be re settled.