So my portfolio will be
d) 0.5 btc (not decided yet)
e) 0.5 btc (not decided yet)
Why don't you try to make a research with XRP or BNB and you might consider choosing these altcoins to finally complete your portfolio. You can also keep your bitcoin as your investment if you can't find a suitable altcoin to invest as of the moment. This might be your best option right now.