Well done on getting to where you are so early in life. I agree with previous comments that you should try to avoid selling.
Provided you have a spare bedroom in your PPOR, you could always get a housemate. Of course it isn't for everyone but plenty of young couples are happy to do this to help pay the bills and get ahead faster. It might give you $7k per year to go towards your holidays.
As you have approx 20% equity in your PPOR, it might be worth looking if there are better loans for you to refinance to. Depending on the loan you've got, it could save you approx $1,000 per year in interest.