Maternity clothing is not known for being stylish, though that has changed a little in the last decade. It is especially unfriendly to angular women with the abundance of soft florals and ruffles and jersey and chiffon. A maternity wardrobe can also be a cost prohibitive investment, because it is worn for such a short period of time, and if you are curating your wardrobe, you're usually looking for investment pieces that will last you many years.
I know of style-loving women who have continued to wear what they normally would, only a size or few up. I think that's a great approach if it physically works for you. It has the caveats of those sizes existing for you (i.e. being in the middle or small end of the sizes range to begin with), and again it risks the issue of investing in pieces you won't be wearing long.
The approach I currently favor is dresses for comfort, midi dresses for length, boxy dresses that have plenty of room for expanding but also look great belted, and knits just one size up with plenty of future stretch. Outside of pregnancy, this approach can also be helpful in periods of changing weight.
For the knits, if you are an angular woman, try choosing thick knits with straighter lines (e.g. sheath) rather than the typical bodycon styles. Sizing up one size can also help straighten the lines. If a dress has a little too much flow or flare, it can easily be tailored into more of a column style when finished with pregnancy.
1. When trying a dress on, pull at the fabric to check how much belly expansion room it has. Wrap or other self belted dresses, knit dresses, empire or high elastic waist dresses, and boxy dresses have the most potential.
2. While you're expansion checking, also look at how high the hem might rise. Shorter dresses might become too short with a big, round belly, and need pants or leggings to work.
3. For boxy dresses, try it with different belts or even a fashion harness. It should look good belted at your waist when you're not pregnant, as well as belted above the belly when you are. Knits are of course easier to wear fitted at many sizes without a belt.
4. Never forget shoes, jewelry, and accessories! They make an outfit, and a pair of cute shoes and earrings can make you feel better even when you're otherwise not feeling so good.
Do you have an F9 or AF type in mind for the dresses or accessories? How have you dealt with curating a wardrobe while changing sizes?