M.,
THis is a very personal decision, as much as it may not seem so. THere are very different philosophies in this country about raising children and I think this is one of the most debated issues: letting a baby cry it out. I am personally of the mindset that a 5 month old is too young to be left to work it out on their own. My son will be 1 next week. He fell asleep either nursing or on my/husband's chest until he was 9 months old. We were, however, able to put him down. In early December, everything changed. We could no longer lay him down while asleep, which sounds like what you are saying happens. We found it helpful to establish a routine for naps and bedtime, lay him down in his crib while awake and then sit with him until he was asleep. In the early weeks, he clutched our thumb until he was asleep. Now we usually stay with him, but sometimes leave. He still likes to hold our thumb or touch us in some way, but not with the same vigor as initially. Someone once told me that babies have an 18 month gestation period, nine on the inside and nine in your arms. Someone else suggested a sling, which could also work for both of you. Whatever you do, there will be an adjustment period. Give it 2 weeks, then make a decision to change. One thing above all else, you are her mother so follow your insticts to do what is right. That may not be what is right for me or someone else. Have fun!
J.