How do i get my breast milk back right

I have been breastfeeding my baby since she was born. I just here recently started using formula and breastmilk. I have been slacking on breastfeeding cause formula is easier but i miss working so hard on breastfeeding and its best for my baby. Since i havent been nursing all day and pumping when i do breastfeeding early in morning and go to pump maybe 2 or 3 hr later its like i aint producing Fast enough? How do i fix this? Keep in mind ive been going half of the day all day not pumping my milk out tell at night. February 24th when i had her been breastfeeding every since my baby soon will be 4 months old