OP - if you are still reading this, sorry you've had a pasting for asking a perfectly reasonable question!
I was much older when I had DC1 in my 30s, but the whole "wear what you wore before" doesn't really work when what you wore before were suits in the week, clothes for big nights out on Friday and Saturday nights then having a few slobbing about clothes for Saturday & sunday afternoon hangovers (didn't really see much of Saturday and Sunday mornings before DCs). A few 'smart casual' clothes for lunches on Saturday & Sunday, but no where near enough clothes to last a whole week. All my money went on work clothes and 'going out' stuff, I didn't have a casual style and did also fall down the Whitestuff/Fatface hole for a while.
My basic wardrobe is skinny jeans/jeggings (add in disco pants if you have the figure for them), long sleeved tees in the spring/autumn, jumpers in the winter and nice tees in the summer. I've got a pile of jersey dresses that don't need to be ironed for the summer that are long enough to cover my arse should I be scrabbling around on the floor with DCs at toddler groups (maxi dresses are good for this). I tend to stick to only a limited colour palate of shades that suit me and 'go together' easily as I don't have time to think in the mornings. I realised the other day I own 4 denim dresses of a variety of styles and shapes, perfect on their own with flat sandals in the summer, add tights, cardie and boots in the winter.
I avoid pattern execept on dresses, I don't have time to make sure things go and am scarred by the "A line jazzy pattern skirt" FatFace stage.
Obviously until your DC is closer to 2.5, it's best to avoid dangly earrings and necklaces that can break easily - bracelets are good for making you feel like you've made an effort without risking harm to you or your DC.
Being a Mother is only part of who you are, dress for the person you are in total, not just one bit of it.