These days in particular, hospitals will probably frown on a nurse taking so much time off. Many places only allow two weeks off at a time, and definitely not every few months. They need to be able to count on staff being there regularly.
Working for an agency is probably the way to go, but with the economy, agency nurses aren't getting that many hours, and most require that you have at least a solid year or two of experience before taking you on.
Age isn't likely to be a barrier, but depending on where you live, a lot of places aren't hiring new grads, period. In time, this will change again.