Hello @ToniaL7 ,
At this time, the ability to limit by tag isn't available for accounts with 10k+ contacts. With that said, it looks like your last few really-big emails you've sent have had enough bounces that you can get rid of them, and reduce your contact numbers back down below the threshold.
If you wish to maintain the higher number of contacts and not remove any of the bounces, the best workaround will be making lists based on segmented criteria. For example, segmenting all contacts based on specific list membership(s) and tags.
I've attached the known service request and submitted it to the engineers for further review. If and when they have an update to this issue, they'll make sure to notify you.