i married my husband when my son was 12. during that time prior, i was a single mother. while a single mom, i completed a double bachelor degree, a master degree and worked full time. my son was in daycare, or with family and friends when i needed to work/go to school.
we managed to make GREAT memories, given my busy schedule.
as others have suggested, it's more about quality than quantity. when together (even for 4 hours before bedtime) i'd turn off the phone, and we'd just spend that time together. in addition, we'd do things like play boardgames, eat "happy meals" make up silly songs....
bottom line, these were things that were "our time." it makes absolutely no sense to others, yet, to us, these silly times and crazy songs, et al, our OURS! and at 19, when we are together, we still laugh at those times together.
bottom line: make the time you spend with her meaningful. mothers who are with their kids all day, are usually not spending all of that time with them.