Help! Sizing dilemma...

This wasn't what I was planning on posting about today, but I'm hoping for some help. You see, last night I was trying to start a new project, however as all my options were (essentially) brand spanking new projects they required tracing off patterns, and I just became completely overwhelmed. I started with re-measuring myself (like a good little sewist) and comparing my measurements to the size charts. I also measured my high-bust as well as my bust, as suggested by many, including Gertie's new book.

I have since, with the benefit of a clearer head after a nights sleep worked out what to do with regards to one of the patterns, the Rooibos pattern as I've I've found a great resource for a FBA to the rooibos pattern on the Colette patterns blog. However, I'm still confused about two patterns - the Jasmine Blouse from Colette Patterns, and the Portrait Blouse from Gertie's book.



If I look at my measurements on the first sizing chart for the Colette Patterns I span a massive range of sizes! My high bust gives a size 4, bust an 8, waist a 10 and hips a 12 (above pic). I know from my previous attempt at a jasmine that I can't just make a size 8 in the bust, as it's way too big in the arms and shoulders, so I definitely need to start with a size 4 there and do a FBA (Full Bust Adjustment).

Looking at the second sizing chart, the one in Gertie's book, I'm almost exactly a straight size 8 if I use my 'standard' measurements (below pic), but if I use my high bust (a measurement Gertie suggests using in the book) I should make a size 4 and do a FBA.

Now, obviously I need to do similar things with both of these patterns - a FBA. However, I have a confession - I've never done a FBA before and I'm a bit daunted. (I know, I know, I should probably have done one by now, but somehow I've gotten away without having to).

There's quite a lot of FBA resources around, this one and this one both look quite good and clear, so how to actually do a FBA isn't the issue. The issue is with the waist and hip measurements - obviously a FBA adds to the waist (and hips in these patterns as there's no waist seam), so do I need to grade out to a bigger size at the waist and hips or will the FBA add enough size in?

The portrait blouse has pleats below the bust (a bit like the Sencha blouse by Colette patterns), whereas the jasmine has no under-bust shaping so the answer is possibly different for the two.

So I guess the conclusion to this slightly confused post is help! Do you have experience doing a FBA? Any advice or suggestions? Please?