In my situation, some months I use very little data and others I use a lot. I find that I am wasting data purchases trying to guess how much I will need for the month. Although Verizon does allow you to change data plans every month I am extremely busy and I find it less than customer friendly to have to babysit my data plan each month. It is very irritating to see data wasted one month and then the next month having to pay extra. I noticed that AT&T does offer data rollover. Why won't Verizon compete here?
Verizon is not likely to have "rollover" data. Even with AT&T's, it's only good for the next billing cycle...you can switch to AT&T, or better yet, Google Fi where you are billed for what you use - @ $10 / GB. You set an allowance, but there's no penalty if yo go over, you are just billed the extra the next month. If you don't use all the data, you get a credit on your next bill. It sounds like that would be an ideal plan for you, since your data seems to fluctuate so much.