Dear friend, welcome to HCM.
no reason to panic.
how old are you?
all increased endometrial thickening (lining) need not be pregnancy
, it has many reasons(including normal menstrual cycle ).
if you are sure you are unlikely to be pregnant, have not missed a period, pl. think other causes first. see your gynaecologist to get evaluated
take care and keep me posted on your progress.
Good luck !