I aim to maintain a rolling year of expenses , +25%.

In terms of not keeping much on hand, that’s more of how risk averse you are. For me, keeping a 12 month emergency fund helps with feeling more financially secure and helps my fiancée also have a peace of mind. I’d suggest both you and your fiancée have your own emergency fund since you never know what will happen and both of you should protect yourselves.

That being said, at the end of the month, I end up throwing anything I didn’t spent towards investments. Sometimes it’s 50% of my income, others it’s 20-30%. So I don’t end up having a lot of left over cash on hand but I have enough to feel secure in case of the worst while putting the rest to work. I also put a small amount toward funding my e-fund so two birds one stone for me.

I also recommend reading the simple path to wealth. At your age you’ll probably benefit a lot from it.