I've been exploring Japanese green tea but I'm still in the process of figuring out what teas and what brewing parameters match my preferred tastes. I am IN LOVE with the various smells of sencha - nutty, grassy, sweet, buttery, oceany, salty. But honestly, once brewed, it's not as enjoyable to me. I've gotten it to where I usually enjoy the first few sips of each infusion, but halfway through each cup the flavor changes and the bitterness starts to creep in. I could go back to genmaicha (always yummy to me) but I really want to figure sencha out! My dream is to master brewing a sencha that tastes EXACTLY like it smells

I've been experimenting with different light/medium steamed senchas and fukamushi senchas (from dens and o-cha) and using the recommendations given with each tea, but there's so many different parameters to play with each for tea type - it's a lot of (expensive) work to sort out! Is anyone else out there bitter sensitive or prefer the nutty/buttery flavors the most? Any recommendations for either specific types of tea to try or general brewing parameters?
I've experimented with different tea/water ratios and temps, but it seems like, in general, all I've figured out is that I like the flavor of a short infusion (10-20 secs)- though sometimes I feel like it's too weak and I'm missing out.
Does anyone else do quick infusions with sencha? Any temps/ratios to try?