It's hard to say not knowing that the product is. Sometimes very small changes are enough to protect you. Also, you really don't have an issue unless the original product is patented. However, if it is a product by another WAHM or small business, then the waters get murkier. You may not be doing anything illegal in making your product, but you may make the original makers mad or may be accused of being a copycat. It's hard to say.