Hello, I Took Hcg Diet Drops On April 15/2016 And

Hello, I took hcg diet drops on april 15/2016 and had periods on 22nd April. While I was taking hcg drops I had light spot for one day on 14th of may and since than I had nothing. I stopped taking my hcg diet drops on 18th of may. I wants to go for my hcg pregnancy test and I don't know how soon I can go for my test. How many days it will take the hcg drops to get out of my system? It's 25th of may today. Can I go for my blood test today? Please help thanks