Is it unrealistic to want to birth 5 kids?

My dream ever since I decided I wanted kids was to have 3 little boys and 2 girls. I have all of the names picked out and they are so unique and special to me. I was a boy to be first I know it will be random but the boy can help protect the other siblings and teach them. We have been trying to get pregnant for about 3 years.. we have had no luck i am 21 and know that I have many years to try. I also know that 5 kids is a pretty big expectation but I plan on having more than just what I birth. I want to also be a foster parent and maybe even adopt a few more kids through the system. I really hope that dreams come true because this is my biggest dream and I am so ready to expand my little family.