Holly, 13 at the time, and her father Angus, 45, were thrown into the loch when the rigid inflatable boat they were in malfunctioned and lurched to one side at almost 60mph in March 2005.
Holly's sister Chloe, who was 15, wrestled with the controls of the boat, turned back and leapt into the freezing water in a bid to save Holly and their father, but despite her efforts they both drowned.
Until now, Holly's mother Hilary had been unable to put her daughter to rest. Last November, a foot was washed up on Inchmoan Island on the loch after storms and heavy rainfall.
Scientists at Glasgow University conducted DNA tests and earlier this month announced that it belonged to Holly.
Subsequent searches have failed to locate any further remains of either Holly or her father.
Yesterday about 200 mourners packed into Baldernock Parish Church in Milngavie, near Glasgow, to bid a fond farewell to the popular teenager.
On flowers left by Holly's mother, a message said: "To my loving Holly. I will miss you and love you forever. Lots and lots of love xxxx"
One from sister Chloe said: "To Holly, missing you more and more every day. Lots of love xxxx".