The f1.4 is not worth it the 1.8 should suffice.
I think now you should invest in a quality flash and a remote shutter release.
Going to a fast long focal zoom is another can of worms worth lots of money.
On the other end if you are going to trake pics of inside homes where the wide angle lens
is to be used and the kit lens is just not wide and sharp enough..that is also another barrel of cash
for say a 10-20 sigma.
You did well on the intermediate money making lens