If reincarnation is real, then how come the population has grown?

In my religion, there are souls in Heaven and people on earth with souls. Reincarnation is a choice whether to stay in Heaven or to come back to gain "gnosis" or knowledge. The more knowledge and understanding you have, the closer you can get to God. God's light (love) is so strong that in order to withstand his light and be able to see Him, you have to be reincarnated several lifetimes and gain knowledge so that you can come closer to understanding and feeling the unconditional love that God has for everyone. He doesn't single out certain people to love. His love is for everyone for infinit. We reincarnate to understand other people and to go through our trials and tribulations to reach this goal of understanding. Everything we go through in life is written in our life chart before we decide to reincarnate. A person who decided to put a lot of suffering in their chart is someone who probably wanted to gain a whole lot of knowledge. Not everyone decides to reincarnate so there are many souls in Heaven. Enough to fill this world and probably 10 more. So, the reason the population has grown is because more souls have chosen to come back or we can go another route and say that maybe the population really hasn't grown at all. Maybe because of advanced technology, it's easier to count people more accurately. There are still a large amount of people unaccounted for though.