Oh wow, I love this on you. You look amazing in pink and I want that top! I don't think it looks like a tent, especially paired with skinnies. I am enjoying wearing this silhouette because even though my arms are not good at all, (I'm embracing them, ;)) I think it helps to mask some of my large hips/thighs. And it's comfy. Your arms look great BTW. But I totally understand about feeling large next to tiny people. I am on a committee with two of the tiniest ladies I've ever seen, both are short little toothpicks. I think size 00 is too big on them. I feel like a giant blob every meeting and I'm only just over 5'4" myself. Like you, when I need a boost I reach for heels, definitely helps.
If my bra straps show under tops I try fashion tape. If that doesn't work I wear my strapless bra.