With american labor being expensive, adding a room to something that is 1236 sqft seems it would be too expensive to do. Suppose it costs $100k. You're looking at $700k for something roughly 1800sqft. Not worth it imho, particularly there's nothing special about this home (not ocean view, beach front, etc).
I like the location of the 1236 sqft house, but it seems a little small for a SFH. You'd probably outgrow it quickly once you have 1 child. For me, I would pass. If you want to go that route and feel that you need something soon, you might as look into a 3 bedroom attached townhomes that are dropping in CV.Townhomes are oversupplied and overstretched in CV. I'm personally hoping for sub-$600k homes to be more prevalent in the future, but I'm not going to say you shouldn't buy now- Personally, I believe in that you buy when you can afford to buy and what you want. 1236 sqft 2 bd seems small for a family of 3, especially if you want one room for an office/den.