M.
Skip the toddler bed. We went right to a full size so we wouldn't have to buy another bed. She loves it - but...my husband thought it would be helpful for her in the beginning to lay down with her until she became comfortable with it - needless to say at almost 4 - I, not my husband, is still laying with her to get her to go to sleep. this is a kid who went to bed wide awake from the time she was 4 weeks old until we put her in her bed.
I never had concerns about her falling out - we bought the side rails so she can't.
Good luck