Internship Attire for Women?

Going into my junior year summer, and I’m your typical broke college student so I’m scrounging to afford office attire. I’ve got a black blazer and several black trousers, and I was wondering if it’s ok to mix and match them even though they’re from different brands. The dress code at my office is conservative and I heard that mixing and matching black attire is a no-go, but just wanted to check here. Cheers!