Hi OP
I don't know how helpful this will be to you but just thought I'd share in case you can take anything from it as I'm a size 12-14 with young kids too. I'm 5'8, not sure whether that counts as tall but tall ish and I'd say I'm most comfortable in classic/casual/sporty as well. I buy stuff so that I can wear almost anything I own together - so I don't do 'outfits' just lots of mix and match, because otherwise I find the washing / outfit prepping too hard.
So my main go-to's are (depending on season):
Shirts: a couple of relaxed fit linen shirts and a few more fitted cotton shirts, which I wear with any of the bottoms I have, variously fully tucked in, half tucked in or completely untucked. I never iron, just wash and hang.
T-shirts: a range of basic crew necks in colours I enjoy wearing and some looser tunic/sport style ones
Other tops - a couple of boatnecks with elbow length sleeves in nice fabrics, some long sleeve tops in lightweight wool for layering. Couple of silk things for if I ever want to feel dressed up.
V neck jumpers and slouchy cardigans
Jackets - ALL the jackets, I reckon they make the outfit. A bomber, a puffer, a sporty windbreaker, a trench, a longline waterproof warm thing, and a couple of light mid season short coats/jackets just for funsies
Jeans: higher waist, wider leg
Trousers: tweed style wider leg (I have some brown and some mid blue) and black tapered
Shorts: Cotton chino style
Joggers: Bamboo soft joggers
Skirts: a casual soft cotton jersey above the knee and a linen blend one just below knee; black wool short skirt, long bamboo maxi, printed floral maxi
Dress: Long floaty linen thing with waist tie, knee length shirt dress, wool shift dress
Hats / caps / scarves / tights etc
Trainers that are comfy in a few colours; boots, loafers, sandals
These get me through pretty much everything and I feel like I have lots of options every day. I think for some people having set outfits works best but for me this way works really well.