Should I Quit?

I'm kind of getting tired of this place. First of I started working at this nursing home as a C.N.A. When I went and got L.P.N certified, I asked if I can work there as a nurse. Well, I kept getting answers like the head nurse isn't here and she's on vacation but when she comes back i'll let her know. So called the head nurse and her response was "Oh we were just about to call you. We'll call you back with when you can start." So 1 month goes by and I figure they're not gonna hire me because I'm shy so they figure I won't do a good job. Fine I accept it and move on by finding other jobs. I get accepted two job offers a month later at two rehabs. On that day my job calls back and says, guess what congratulations can start work tomorrow morning. So I stay with my job and decline the other two offers. Since I started working as a nurse they always send this nurse to check to see if i know what i'm doing. Meanwhile the other nurse asked for a position and they hired her before her license came in the mail. Now 4 months in they have me doing a skills check list because i made mistakes. They have the new nurse doing some skills with me to make sure i know what i'm doing. After I do the skills they're like way to go you did it. I feel so stupid and embarassed because while i'm getting skills evaluated the other nurses are laughing at me. They tell me i need to think like a critical nurse they know i know my stuff but i'm just not getting it. They also say we're not trying to insult you I know you compare your self with the other new nurse but she's a different entity. Don't feel insulted. They also recommend that maybe i should work on a med. Surg floor. I am so pissed off because if they felt this way from the beginning why hire me. Who knows maybe it would've happened in another facility. Should I quit or am I takng this to much to heart.