Is it normal for a positive to disappear after an hour?

Hi doc! I am 10dpiui. I took a test yesterday and got a very faint positive. I took another one today and it took just a minute for another very faint positive to show up. Then after about an hour it disappeared. Am I pregnant or not? I'm thinking that maybe because its so early there's not enough hcg in my urine. What is your opinion? I am planning on testing again at 14dpiui. Maybe it will be darker by then.