Pixel 3 user here. I pay $30/month on average.
What on Earth are you torrenting on your phone? I've never used more than 5 GB data in a month. Just wait till you're back on wifi before watching YouTube...
I had a family plan through t-mobile and after years of getting more expensive per month (no enterprise discount, increasing number of taxes/fees, etc) I switched to google fi and halved my bill.
Some tips for those trying to minimize bandwidth: 1) tell google phones to backup pictures/videos on wifi 2) preload maps for any cities you visit more than monthly 3) get a podcast app (if you listen) that preloads them when on wifi 4) get youtube red ($10 a month) for no ads, downloadable youtube videos, and downloading your top 500 songs.
With the above, even when traveling quite a bit I average 1-2GB a month. I generally use nav every time I drive just to get the traffic info/warnings.
Good for you.
I'm on WiFi at home and at work, and I just checked my bill and I used 5.53GB last month, and my wife used 9.72GB. I don't consider either of us to be heavy mobile users, especially since we can't get cell service in our home.
For cost-sensitive people who are content with T-Mobile networks and open to MVNOs, I suggest looking at Mint Mobile. The best ongoing rates are had when you buy in bulk: $15/20/25 for 3/8/12 GB LTE per month, as a 12-month package. It also has unlimited voice/sms, and it throttles rather than charging extra when you exhaust your LTE quota.
Oh, and they also support T-Mobile's WiFi calling, so you can have phone service in your home without cell signal...
If you have a spare phone, I highly recommend a Mint trial. There is a 7-day starter pack, which gives you two SIMs and lets you test briefly with a temporary number and then reactivate on the second SIM if you wish to port in your existing number. But, I thought the $45 pack was so cheap that I used it for a longer 3-month trial, after which I was happy to keep it alive as my new main service.
You also have to think about whether you care to keep your old grandfathered plan, i.e. on a backup phone. I kept mine because I can keep it alive for $5/year if not using minutes. But, I imagine I may drop it some day if it cannot be relied on to actually place an emergency call...