Days with fewer pump sessions

My 6 week old has started giving me sleeping stretches at night of 3.5 to 5 hrs. I pump during the day every 2 or 3 hrs for about 15 to 20 mins. I have always been on the lower end of supply... my supply has gotten better but now hes also sleeping longer at night.. I don't wake up to pump at night and typically pump after I feed him. My husband works nights and sleeps during the day so for an exception of 3 or 4 hrs daily (time that hubs is home and awake before going to work) I'm on my own. This is why i don't put alarms at night to pump if he sleeps because I'm typically dead too. If I increase the length of my pumping sessions, can i avoid my supply going down? I honestly can't afford for it to decrease and if I need to set up alarms I will. Please share your experiences with this.