I don't have your body type, so my suggestions may not be as helpful, but here:

Have you tried a Beltaway? It's a stretchy belt (so it won't budge, whether you're sitting & standing) with a slim buckle (so it should fit cleanly under your tops without adding any bulk around the waistline closure).
They have their own website or Amazon:

Here's a tutorial so you can see it in action - you don't have to tuck your top (like in the Instagram video) but it does prove it doesn't move!

Speaking of which, have you checked out Alison Gary? I linked her IG above but she also has a blog called Wardrobe Oxygen - I find her tips relatable because she doesn't have a model's body:

You mentioned that dressing for wintertime is easier than hot weather, so here are some tips on how to hide your belly during summertime:

Since you said you're more of a visual person, here's a helpful post of the SAME model in different clothes to visualise how different cuts drape:

My last tip would be to not be so hard on yourself about gaining weight & having to 'relearn' how things fit - it's all a process. I know you may not be there yet, here's a helpful guide on tucking demonstrated on Allie herself:

Hope you managed to glean at least something useful from all that (or that you report back honestly if not)!

My advise would be everything gently tailored or slightly fluid---but NOT empire. Textured, more structured and thicker fabrics rather than thin, flimsy and plain. Some prints, or patterns, including a strategically placed geometric print on a simple tee or sweatshirt (on front bust). Hip length tops (not tunics!) with no tuck or an slightly elasticated hem on hips and enough length to slightly pucker over it. Then layer something on -depending on your wanted level of dressiness-an open button down shirt, a blazer, taillored gillet/puffer waistcoat, various cardis (don't need to be old fashioned crew neck- try V-necks, or straight down style, cascade etc). Open knits can help in summer for providing a second layer even in the heat, but think everything longer (or long enough!) and nothing really body con--but show a bit of skin with cuffed and scruched sleeves or some cleavage. Bottoms more structured, slim and tailored (say cigarette pants) with some elastan in the fabric and/or some elastic on waist- including all sorts of casual tube skirts- (nobody will see your apple shape if the elastic on waist is comfy and will not cut in- so rather size up and take in sides to hem for more shape if you want) or even wider cut pants that are now on trend --perhaps showing up some ankles-or cowering some glam pointy toes. Mostly saturated colors-it doesn't have to be all dark! Welcome to the YLF!

Hello MIchielles and welcome!
Other Fabbers have already said it all. I am a rectangle with apple tendencies and I also recommend fluid, slightly flared, longish tops, pants with stretch or draw-string pants, fluid dresses. A cardigan or a soft jacket also helps disguise an apple belly and creates some shape.
You have beautiful hair !