When I think of "pale coastal blue" I think of a shade that is a bit more aqua than "baby blue." Can you clarify which you want? If you are looking more in the aqua category, I like some of the following:

It's going to be difficult to find the right shade you're looking for without seeing what your room looks like and what other fabrics/colors are involved. I would suggest you go to your local paint store (I prefer Benjamin Moore) and bring several paint chip samples home to see what will work in your space. You can also get some large white poster boards and small paint sample containters to create your own sample boards which will be helpful.

One of the best investments I ever made was purchasing Ben Moore paint fan decks Available online at about 25 bucks . I have all three series. Highly reccomend

I dont want Aqua, Im looking for the palest blue..almost white, I know its hard because there are blues with hints of green-gray-purple, after about 50 samples I finally found the right blue for my kitchen, now Im painting the adjoning living room but dont want the blue in my kitchen