Hey BL, just found this and thought it might be of use. It is various recipes for low and no sugar jam. As I suspected you need the pectin, but should find it at a health food shop or online. This is an american page so there are some links to US shops and webpages for ordering. She uses splenda, but I have also seen and used when it was launched a really good product called Fruisana - you can get it in most supermarkets, it is very low GI fruit sugar and it is great in cooking and baking. Anyway might be worth a try!!
How to make Jam Without Adding Sugar (Using Splenda or Fruit Juice)
Might be good to try and certainly a lovely healthier alternative.
And another version:
Low Sugar Strawberry Jam Recipes | Home Improvements and Gardening
Happy Cooking
Jez
xx