Your portfolio has good coins to hold until bull run but you don't have BNB yet. So try adding this coin, it's one of the established and worthy to include in our portfolio (but still DYOR). The market is declining so yes a good time to keep buying, I suggest to buy additional coins only for established coins like BTC, ETH and BNB and stick to it until you had a good amount of holdings.

Your goal is to have sufficient money to buy an apartment and it's not a small amount. We can't predict what coins will have a huge growth during bull run but as long as you're holding a coins with potential, you'll certainly gain from it. Thus, be wise on what coin to buy monthly with your allocated budget.