What you plan to do sounds easily doable with an OW RTW.
But it seems a bit of a waste. You actually have 16 flights. This is usually enough for 8-10 real destinations. You also have one year to use the ticket.
Assuming you are in Eco you should compare the cost of one way flights. With this few destinations this is often cheaper, does not restrict you to flights on Oneworld and most likely allows you to take more convenient flights.In Business Class a RTW ticket usually turns out to be cheaper.
Google flights is a good tool to search for one way ticket prices and also by setting the filter to Oneworld for OW flights.
You could also consider doing Thailand or Vietnam for beach instead of Barbados. Other fun places on the way are Capetown, Hong Kong, Sydney and many more. But that comes down to time and personal preference. The advantage of an RTW is that you can add these places to the ticket for not much extra money (mainly the taxes/fees).