When I first started diving, I had a similar plan for my diving future, with even fewer trips than you have planned. As I searched around, I saw that it would not cost me much more to get gear that would also fit the bill if by some remote chance I decided to get into it more than I had anticipated.
I got into it more than I had anticipated.
Having planned for the diver I might be instead of the diver I was, I had almost no wasted money. I didn't have to say, "Shoot! I wish I had bought a [insert name] instead of [insert name].
Good quality scuba equipment is incredibly durable. Counting pool training sessions, I would guess my mask has 1,200 dives on it. My primary computer is 10 years old and working great. My current BCD has about 300 dives on it, and it looks remarkably new. Whatever you buy will last a long long time if you take care of it and--more importantly--if you make a wise choice to begin with. If you don't make a wise choice to begin with, we'll be seeing it on eBay just after you decide you really needed something else.