Very interesting. Here's my take as someone in a very similar situation (20's, DC, same income level, similar NW, moving into a rental with gf this month).
30-40k will be a bare bones, absolute minimum 10-15% before transaction costs down payment on a reasonably sized 500-600 sq foot 1 BR in most neighborhoods. I'm sure there's still some better deals out there but, that seems to be going rate.
Is DC one of the "safest" housing markets in terms of value preservation and appreciation upside? Yes.
If I was sure that I would be in the city for the next 10 years, would I try to buy? Yes.
If I had $2 million to burn would I buy a pair or rowhouses TODAY? Yes.
My point is that there's value to be had but, the barrier to entry is very high and in many ways the potential financial gains are offset by the illiquidity of the investment and how overleveraged you would be.
That said, if you're SURE you'll be staying 10+ years then the payoff is likely there (pursuant to full mathematical analysis) but, and this leads to my main point, how sure are you?
The crux of this equation is not the financials - it's the state of your relationship with your SO.
How certain are you both that your careers will stay in DC? You're both committed to raising kids in the areas and staying 10+ years but, you're not sure if/when you're going to move in together? Seems like the cart is before the horse. Buying a place together that is large enough for you both to live in appears to me to be a superior option to buying a tiny place for yourself and then, a year later, having to rent that place out to cover half the rent in the new apartment you share with your SO. But, it doesn't sound like you're ready for that.
Moving in with your SO and paying reasonable half rent is what I'm doing. Then, if things progress well, and you two decide to stay in the city long-term, you can buy a place together. At that point you'll have more financial resources, more certainty about the course of your careers, and will be able to make a better joint decision about what you want in a home.
Buying now just locks you in big financial burden and limits your options later. The financial opportunity may be there but, the risks, especially re: your personal life, may be just as big.
Anyway, PM me if you want to share more details or talk further.