I think at you and your wife’s stages of life, career and family (all developing and growing), your preference for the lower rent option is smart — not because you’ll have more money to “do the things [you] love, like travel,” but to avoid taking on more debt.

It’s always a bad idea to count on future higher income when making decisions about present consumption; it leads to borrowing that sometimes does not get paid off later, but simply rolled over.  Incomes sometimes don’t grow as hoped, and unexpected expenses come up.  (I know this from personal experience.) 

Try sacrificing the house space now in order to make it more likely you’ll safely afford a nicer house later.