Most of us tend to be top-heavy rather than bottom-heavy, so look for nice outfits that create curvature to counter that. For example dresses with sashes, coats that widen at the bottom, corsetry, etc. you generally want to avoid anything that straightens your silhouette. The aim is to give the illusion of fuller hips and a narrower waist.
But also remind yourself that most women (cis or trans) are not the pristine, soft-spoken, glammed up doll-like beauties the media likes to pretend we are! Women can be loud, women can be butch, women can be muscular (π be still my gay heart). Try not to be too hard on yourself.
(I've been trans for 10 years, ask me about anything!)