No sex drive...Help!!!

Hey ladies/gentleman... So im 29 ive been married for 6 years with my husband for 9 i have two boys 5 and 1, i work 4am to 1230 so i have to wake up at 2am to make it on time to work...lately i havent been feeling like myself... I have no sex drive and i just feel numb, i dont know how to explain it. So my husband tells me today that he feels bad for always having to ask to have sex with me cause we only have sex like 3 or 4 times a month and he has to ask for it, I really dont know what to do... I dont want to lose him... Does anyone have any ideas to help me get my drive back!!