(lurking... I am close to 2nd tri, but not quite there)
I used to work as a bra fitter at a department store (similar quality to Macy's), and I noticed that no one has mentioned yet how to troubleshoot your bra's fit. If the straps are falling down or uncomfortable (and adjusting them doesn't help) then you have a problem with the band size. The band on a brand new bra should be snug without putting a painful amount of pressure on your rib cage when fastened on the loosest or second loosest hook. If it's too loose, you'll notice the band riding up in the back and your straps falling off your shoulders. If it's too tight, you'll see red marks on your skin after taking it off, and a lot of the "muffin top" look on your back while you're wearing it. The cups should fully contain all breast tissue without any gaps or spillover.
Also, I know that there are tons of online tutorials on how to measure yourself for your bra size. Do not use them... you will most likely not be able to get an accurate measurement by doing it yourself. Your best bet is to go to a middle to high end department store or a lingerie store to be fitted, and make sure that your fitter knows that you are pregnant so that she can suggest the most comfortable options.
As far as maternity or nursing bras are concerned, use your best judgement on what feels best and makes you look the way you want to look. From what you said you wanted, it sounds like you want a pushup (for the lifted look).
Hope that helps, and good luck.