When can I re-test? I want to know?

Ok so i know i have asked alot of questions but the more and more days that go on I get more signs. I had my period on the 2- 5 of november and it was light for me. My husband and I had on the 9th, On the 16th about mid day i had to go to the bathroom when i was going to the bath i had noticed a brown discharge on my under ware. I have been cramping since the 10th of Novemberr to the 16th of november. Today is the 19th and last night when i was getting into my PJ's my are starting to hurt a little more. I have to be almost every 30 mins since the 17th and I am very sleepy to. My cat she has been around me alot as well more then normal she always lays next to me now. And this morning when I woke up she was laying and sleeping right there next to my right by my belly... I also took a pregnancy test on the night of the 16th too it came back negative... When is the next time I can test and get a correct result? My husband and I really want this and we are very excited. Everyone keeps telling me that I am so when can I test again or should i have blood work done? or even both? Thank you for all you answers