Is it that abnormal to fail your driver test twice when you just turned 18?

I never got much of a chance to get my license when I was younger because my parents couldn't afford the insurance so I had to wait until now to try and get it. The first time I didn't stop correctly once, didn't look back when I was backing, and didn't slow down enough when I came to the railroad. The second time (today) I got all of the signs and everything right but I made some stupid moves. First when I was leaving the office I almost backed into a truck because I didn't go out quickly enough and was so stressed I forgot to look. Then she said I still wasn't backing correctly (I looked over the wrong shoulder), made a jerky stop in front of the railroad (thats a little picky IMO), and went 5 over the speed limit at one point. I thought I had practiced these things, and my mom said I did well when I was in the car with her so I don't understand the problem. I drive perfectly fine when I'm driving with my mom and they don't remind me to do anything its just that drivers tests make me nervous and thats why I don't p. I'm honestly in tears now and feel really bad because my dad took off work to take me to do the test and its my birthday and I feel really immature any advice, suggestions?