sleep advice for baby!

Okay I'm at my wits end with my daughter. she's 9 months old and getting her to sleep is a NIGHTMARE. I dread Naps and bedtimes. she refuses to go to sleep. she will go to sleep at 7 pm for about 2-3 hours then get up and scream for about 1-2 hours then sleep for about 4-5 hours then get up for another 2-3 and just scream. then she falls back asleep but is then up at 930 the next morning. I work nights so you can only imagine what this is doing to me mentally. At her drs appointments, she checks out perfectly healthy. no ear infections, no fever, no teething. I often think this is what hell must feel like. she's been doing this for about 2 months now. can someone please give me some advice!? maybe you have gone through this? We are trying to let her cry it out but oh my hell I don't know how much longer I can take. I can't really ask my husband because he has to get up at 630 the next morning. like for instance, she woke up tonight and has been screaming for 2 hours. she's been awake since 305 am and it's now 510 am.