Are there any recommended agencies or individuals to help us to develop our own cryptocurrency ?

I'd say you need to start with validating your marketing strategy before you decide whether to build a new cryptocurrency. Your research will inform you what conditions will be required for your currency to succeed and what level of effort will be required to get it there. It tells you whether you have a business or not. Validating your marketing strategy costs you almost nothing other than time. Developing a product costs a lot. That's why you need to do them in the correct order. You may find out that you shouldn't proceed, and you'll have saved huge amounts of cash and effort on a product that won't meet your goals.