If I’m a fashion designer which legal step should I take to protect my business, business name, logo and products/creations – copyright, trademark, patent or all 3?

Trademark protects business names, logos, slogans, and characters or other graphic elements used to identify your business: you would trademark those elements. It will not protect designs or products, just the "mark" used on them. For example, the "Coach" bag company has trademarked Coach, but cannot trademark its bad designs.
Copyright protections original creative works, including non-verbal ones: you may be able to copyright you designs. Copyright is narrow protection, so really only protects that exact design, and the design must be completely original, which is a high bar to get over.
Most patents are "utility" patent, which protect functioning, not design--so if you came up with a new type of zipper or snap, etc. you could possible patent it. A "design patent" can protect designs of manufactured objects, but will only protect the original elements--again, this may be hard.
Trademark and copyright can usually be obtained for $1,000 - $2,000, for both to the U.S. Patent & Trademark Office and legal fees. Patents require much more support and a more specialized attorney to get and can cost well over $5,000...even over $10,000.
Here's a link to the PTO website that provides a really good overview. You should read it, then pay for an hour long consultation with an intellectual property attorney who can answer your detailed questions.  
https://www.uspto.gov