I have difficulty putting my 2 month old baby to sleep unless she is in carrier. We basically rely very much in carrier to put baby to sleep. But I don't like the idea of using carrier always for fear of future spine problem later on when she grows up. Any other ideas on how to put new born baby to sleep? So far I tried putting her in bouncer, baby swing, lying on her back, sleeping on her tummy, all these didn't work. She didn't even feel sleepy.

You can latch baby to sleep or just carry her. They need the security to let them fall asleep. Another way is to swaddle her. I have a few friends swaddling their babies to sleep and it is known that babies tend to sleep longer when swaddled. If you are using an ergonomic carrier in the right way, there should be no worries on their spine development as it caters to their body. My baby have been using a carrier since 1 month old and he is 8 months now.