You can't use the 14/15 losses to offset the 13/14 gains...

You can't use the 14/15 losses to offset the 13/14 gains unfortunately - the order of realisation needs to be the other way around for gains to be reduced by losses between financial years.
You can choose which parcels you match against each other to minimise gains. Gains realised after holding for 12 months can be discounted by 50%.
Having said all that, you're probably best off getting advice from your accountant/tax agent rather than this forum