Is my girlfriend right to be upset?

Yesterday was her birthday, so I took her to chilis for dinner, n I asked the ppl to sing to her n they did, n brought us a sundae that I thought was free but the cheap bastards charged us, anyways.... after, we went to my house to see jackass 3, then I gave her a lil present. I started working about a month n half ago on third shift (11pm-730am). Ive been sorta tired lately cuz of the schedule,.cuz of my responsibilities at home, my addiction to working out, planning dates with her every sunday tuesday n friday, school for 4 hours every tuesday, working six days a week fulltime, Today, well, last night we were at her house at 9 waiting for me to leave for work, we were sitting on her couch with the lights off, wasnt too dark but I started getting sleepy, I sorta fell asleep like at 9:20 for like ten minutex, I woke up to see her with a sad face n tears in her eyes, she said she couldnt believe I fell asleep on her birthday, I would fall asleep on the ladt minute of our dates various times but she didnt mind cuz I always wake up in a bit, bur she said all she asks from me is 1 day of me not falling asleep, I understand but tuesday I only slept 5 hours n then went y to pick her up for about 3 hours of school n then to work for 8 hours n half, next the day wednesday (today) I only managed to sleep 4 hours n a half, u could see why I was tired right? we sorta argued.a lil n I was trying to ecplain why im tired,.but she says ever since I started working ive been lacking energy n she misses me, my energetic self. I understand its her birthday but did she really have to act like that? Pushing my arms away when I was trying to hug her, crying like if I cheated on her, thinking I dont care about her.... We both love each other very much, but is she not understadibg my situation? Ps. Im at work right now heh