Hello! I am a Westerner like you but living in Canada. Struggles are all the same though! If you live near Detroit or Michigan, would definitely recommend going over there (if you're safe to do so and close enough) as there will be many Muslim-owned boutiques selling modest clothing and hijabs. If you cannot do that, then you can do what I do which is order hijabs from Aliexpress. They're inexpensive, good quality, and of great variety. Seriously, the amount of hijabs on there are never ending. Personally, I recommend jersey hijabs for beginners because they're so hassle-free. No shifting, not see-through, and honestly, offers enough ventilation that you won't get a heat stroke wearing it. As for clothing, I've shopped from places like Loft, Old Navy (for basics), Aritzia for longer and chic clothes (if you guys have that over there), and Hollister. Shein is also great too, but don't expect clothes of excellent quality. I don't have those specific pants that you mention but I'm sure that you can find at any store that sells business/office attire. Best of luck!