In September I will be embarking on 10 months of travel with my girlfriend starting from hometown of London through South America, Fiji, New Zealand, Australia, Japan and South East Asia.

Here is our itinerary so far:
Flexible / Rough Dates Departure – Destination
15-Sep-2016 London Heathrow – Rio De Janeiro
14-Dec-2016 Lima – Los Angeles
19-Dec-2016 Los Angeles – Nadi Fiji
2-Jan-2017 Nadi Fiji – Auckland
1-Feb-2017 Auckland – Sydney
22-Feb-2017 Sydney – Tokyo
10-Mar-2017 Tokyo – Singapore
8-Jul-2017 Singapore – London Heathrow

So far our quotes for all of the above flights are coming in around £2500($3500) each does that sound about right?
Ive used Google Flights and many more and it seems an okay price, but Im just feeling like my lack of background is meaning Im paying more for these certain dates, or not taking the most optimal route?

Our total budget for this whole holiday is £14000 each ($20000), again, is that roughly right?

(Not a new redditor btw, a new account for this purpose).