Fit check w/pics - 32DD

I recently discovered this subreddit and decided to give the refitting a try. I had originally been told by a department store measurement lady that I was a 36C so that's what I've always worn. A few years ago, I thought the 36 was too big so I went down to a 34C. I followed the fitting guide from the sidebar by MyWifesBusty. I came out with measurements of 31" underbust and 36" bust. According to the calculator over at Sophisticated Pair that's either a 30E or 32DD.

I decided to give the 32DD a shot and ordered a cute Betsey Johnson bra from Nordstrom. I'm not sure that it fits right.

Here are some pics. The gray polka dot bra is what I consider to be my best fitting old 34C bra. The black one is the new 32DD.

I have two issues with the new one.

1. I feel that the bra flattens my breasts a bit, like the effect of a sports bra but not as severe.
2. The bra creates a weird roll of armpit fat, which I've never had before. I tried to do a close up on that in the last picture, but it's sort of hard to see. It's more pronounced in person.

So what do you guys think? Do I need to adjust my sizing or is it just the style of bra that I purchased? Should I remeasure? Am I just not used to the new fit? Also, apologies for the crappy photo quality, I don't own a real camera. I can try to get better shots, if that would help. Thanks!