Can someone tell me if this will work for 34b small saggy boobs from breastfeeding? I need it to at least pull them up a bit.

This bra doesn't have much support. I wouldn't recommend it if you need lift support.

If you get the correct size for you. I'm a 34 D and it fits. I seriously would have never been able to wear the dress I got, if i didn't have this bra

I see a lot of reviews stating this bra runs big. Is that big in the cup or big in the band? Thanks

I would say more in the band an straps not the cup. I'm a size 38 D and the large fit good in the cup but the straps could be a bit tighter. All in all I am glad I made the purchase for the price it's great!

Does look have a underwire

No it doesn't. I don't believe you can call this a bra haha. I'm a size 34D. The "bra" bent out at weird spots so it just made me look like an awkward, pointy, lumpy robot alien. Yeah, definitely not a bra. More like some piece of scrap someone threw on the street and someone decided to pick it up and resell it as a bra because hey why not. More info than you asked for. But if you have boobs bigger than 34D maybe it will look normal.