Sleep training help

I need some help. My baby will be 6 months old in 2 weeks and is an awful sleeper. She sleeps worse now then she did as a newborn and i am exhausted to the point that my work is suffering. There are some nights that she does well and other nights she's up every 45 minutes and i just dont know what to do anymore. We have a consistent bedtime routine, her wake windows are appropriate, she naps well during the day, but at night she just wont sleep for very long. She has a mini crib in our room and we occasionally co-sleep if it's a particularly bad night.

I always said i wouldn't sleep train but I'm desperate and so exhausted. Does anyone have positive sleep training stories? What worked for you? What method do you recommend?