Cravings!!

Hi ladies, so I'm 12weeks pregnant and having our first scan in two days time!! soo excited! 😊 I've been feeling really drained lately.. like really  exhausted, to the point I actually fainted yesterday at work! but since then all I've been craving is liver and onions! its all I can think about!! just eating it and the taste!! it's really difficult because I've literally lost my appetite and don't want anything untill now..  But I no it's off limits! 😔 has anyone else been getting cravings like this? would it be so bad if I had just a little bit?? 😩 xx