How often to test?! What am I supposed to feel?!

Bexx
Hi! My period was due last thurs never came. I took a test last wed and it was bfn. Soo should I retest? If so when? Should I feel any symptoms yet?! If so what should I feel? 
If my period never comes and my cycle is messed up what should I do? I read that drs won't help unless u are trying for 12 months. Can I lie to the dr and say it's been 12 months?!