I'm 5ft2 as well and have found it a nightmare, even shops that do petite ranges and maternity ranges don't seem to think there needs to be anything for both! I've had to rely on eBay a lot. Next, New Look and Mothercare are quite good for maternity stuff and do petite sizes in things such as jeans, although I've had to buy on their websites as not found any in the stores.
Someone on here once recommended the Eden jeggings in Dorothy Perkins, they're not officially maternity but they are stretchy, and come in petite. I bought a pair of these in black and one in grey in a size bigger than I would normally buy, and wear them for work with the waist band folded over. They've been great and still fit fine now at 26 weeks, I just wear long tops and cardigans over them.
New Look are very reasonably priced and have a large range of maternity stuff online, they have loads of different styles and lengths in jeans and trousers.
I found under bump annoying to start with as they seemed to sit a lot lower than my bump and fell down a lot, but now bump is bigger they're fine. I found a really comfy pair of jeans in New Look that said they were under bump, but the band was thick elastic that actually sat across the middle of my bump and although they were very comfy to start with, baby doesn't seem to like where the band sits and kicks at it constantly when I wear them!
I think different styles suit and fit different people better than others so it can be a case of trying different ones til you find which you like best.