Maternity clothing is kind of a racket. My advice is aimed at making your shopping more cost-effective and comfy.
First trimester- Non-maternity tops and maternity pants
Skip the belly band. You're going to have to give up and buy some maternity pants eventually and they are so much comfier. First trimester you want to wear loose fitting clothes, but not maternity tops or dresses mostly because you don't want people guessing your secret. If your clothing isn't sufficiently loose, it's a better investment to buy loose non-maternity clothing (either drapey or a size bigger than you normally wear) because you will want to wear this clothing again at some point after you have the baby. For pajamas, I have found nothing beats the maternity leggings that go under the belly.
Second trimester- All maternity clothing
Go ahead and buys some cute maternity tops and dresses. I recommend short-sleeve shirts and dresses. You might choose to avoid sleeveless things because your arms might get really not-cute. Skip long sleeve if you plan on having a second child one day because you might be pregnant in a different season. Buy non-maternity sweaters instead (better investment). Long or "boyfriend-style" sweaters will last you into the 3rd trimester.
Note that maternity shirts and dresses with the cute ruching on the side can only be worn when you're pregnant. The shirts without it can be recycled when you're not pregnant.
If most of your pregnancy is during winter in a cold climate you will need a coat- either maternity or a big tenty swing coat (I have the latter). Don't go cold- prioritize the coat. (I kept trying to squeeze into my regular coat during my first pregnancy, so much happier this time with one that fits!)
Oh boy, good luck. One hack I discovered is that if you get really big for maternity shirts, a plain-looking night shirt will look just like a regular t-shirt.
After the baby is born
You will likely be wearing your second trimester maternity clothing and your loose-fitting non-maternity clothing for a while. You'll probably be sick of maternity pants, so celebrate when you can fit into your fat pants again.
My last pregnancy advice posts were about what I suggest you do before you get pregnant, and when you first find out that you're pregnant.