What is the name of plan you are on? Do you have the 5 GB Share Everything plan or the older Nationwide plan with the individual tiered data plan?
I have the same Nationwide plan I've had for 12 years and then a 5 Gb data plan added to that. Does the Share Everything plan allow me to use the phone as a personal hotspot with no additional monthly charge? I'm pretty sure if I had switched from my existing plan to a Share Everything plan my bill would have increased at least as much as it would if I paid the $20 for the hotspot option.
Yes, the Share Everything plan included the mobile hotspot.
Otherwise you can change your tiered data plan to one that includes the extra 2 GB of mobile hotspot data.