Have you tried to sail any smaller boards than 155 go? I'm not sure how much you've progressed, but I would recommend something like a Carve122. Maybe even 111 (since you're not that heavy) depending on your skill/ambition/conditions, but that might be a big jump from 155. What are your wind and water conditions and what sails will be used most?
Try a couple of 115-130 l boards if you can.