DD is 12 weeks old and ebf. She was 8lb 5oz at birth (75th centile), dropped to 7lb 8 (50th) and took 4 weeks to regain the loss. She's now 10lb 9 and has been on the 9th centile for the last few weeks. Average weight gain = 3oz per week.
HV is pretty much useless... has only suggested increasing my own food/drink and putting pressure on to add formula top-ups, which I don't want to do. I asked if there was a tongue tie specialist who could check her over but she was v.dismissive of this possibility, saying "if she can stick her tongue out, she's not tongue tied" 
I feed as often as I can during the day (every 1.5-2 hours + cluster feeding 7-ish to 9.30ish) as she only wakes for a feed once in the night. I always give both sides. This last week I've been expressing after feeds 2-3 times a day and DH has been giving her a bottle of ebm (only 2-3oz) before bedtime.
The trouble seems to be that she feeds for a long time (30-40 mins per side) and after the first 5-10 mins seems to be sucking without swallowing. Often she falls asleep, still latched on. The midwife at my local (NHS) bf support group says this is fine as she is getting the fatty milk at this time but I'm not convinced. From what I've read on Kellymom/Jack Newman it would be better to switch sides? To me it seems like a waste of time when she could be getting a larger volume of milk by switch nursing.
Any advice would be most welcome...