Whilst I'm waiting for my bfp to appear... I've had Vit D levels of approx. 43 (almost normal but not quite there) for the past year. I've been encouraged to get out in the sun to increase this level and I'm also taking a supplement. I might try Ostelin as you have suggested OP.

WOW! I can't believe your little one is almost here :O

Hope everything works out well, I'll be interested in reading any other suggestions