Roofing issue on summer house help with solution.

[DIYer Newbie]

Hello people in the summer I built a garden room and used onduline sheets as the covering. The problem that has risen this winter is that the water is running back under the sheets at the eaves and I’ve now got puddles of water sitting on top of the vapour barrier under the sheets. I used eaves filler but the water is still getting behind them I’m now thinking I should have installed eave trays but as they would sit under the foam fillers would they actually make a difference to the water running back underneath the sheets and getting behind them. Hopefully some kind knowledgeable people here can help and guide me to a solution 

[Canski]

I suspect that this is condensation and the vapour barrier is not supported at the eaves causing the water to pool prior to discharging in to the gutter.