If your LL won't let you break the lease when you want, then both of you are stuck. If the LL wants to sell ASAP, then she should work with you on breaking the lease at some short period of time after it is sold. Her RE Agent should want you gone now or at least be able to say that you will vacate with X days of the house being sold.

Only an Investor would want a tenant. An Investor would want a long term lease (12 months) on the Investors terms which may not include your dog, the present rent income and a number of other factors.

My bet is that you will see this through until the end of the lease considering market conditions, the time it takes to list, sell and occupy a home and the unlikelihood that an Investor will want you to stay under terms agreeable to both T and LL.