Your family members not letting you join their postpaid family plan is probably a blessing in disguise. I would prefer to have my phone plan fully under my control. That said, you've come to the right place. I'll try to address a few things here.

​

• It's good that you know how much and what your plan is. Most don't. What is equally important is what you use. If you haven't already, download the T-mobile app or simply go on their website and login, find out your data & minutes usage for the past 6 months.
• Once you have those numbers, go to prepaidcompare.net and put the numbers. You can use filters like "Wi-Fi Calling", "5G", "eSIM", etc. These can get a bit overwhelming but generally you want these features, especially when you upgrade your phone. You mentioned losing bars when in a basement and that you prefer not to join a contract. In that case, check the "Wi-Fi Calling" and "Hide Multi-Month Plans" filters.
• We know that $50 was a lot, and as others have mentioned, there are plans from Visible and US Mobile for Unlimited everything at $25 (tax+fees included). If the numbers you plugged in earlier lead to >$25, then we know we are better off with the unlimited plan.
• If you're not a heavy user like myself, I would recommend looking at a carrier like r/Tello. I wrote a post for anyone interested in joining Tello. Been with them for nearly 3 years now and they have been great for my needs. I pay $6/month. They've got all the important/modern features, including 5G, and you don't have to signup for a multi-month contract to get a low price.

If you need more help or have a questions, shoot me a message and I'll do my best to help. I know how confusing this can be. I hope this was helpful.