The best would be to modify the patterns to fit you perfectly. There's a how-to somewhere. I'll post the link if I find it back.

If you are going to sew blouse look which mesurments fits bust and wast, if it will pants or skirt look at size which "describes" your hip. I always do this way. bcs we can't be one size only. we have our personal figure:)

Here's the link: http://www.burdastyle.com/howtos/show/800 Right. You should choose the size according to you bust or hip measurement and then, modify it to fit the waist according to the how_to which I gave you the link to.

I choose my size after the part of my body which is the biggest according to the size charts and then alter it while sewing, because it is easier to take some fabric away than to add it :D

In your case: I don't think it is such a big problem, because the seam allowances are very generous (1,5cm) and everytime I end up taking the side seams in because I cut the fabric too big.
You can also cut between the lines!