Recently,we signed a real estate agent/buyer agreement in Tennessee. The agent is not licensed in Mississippi where we may also be interested in buying a house. Are we forced by the contract to pay her a commission if we use another agent in Ms. before the term of the contract (6 months.) is satisfied?

It doesn't say in your contract? In my state it not only lists the confines of the state but also provides lines for filling in a more limited area.
If it doesn't, you could be in a grey area of commitment and should ask without saying what state you might be looking in. Agents can get referral commissions from agents in states they aren't licensed in.
Of course you are PAYING this agent, so should not expect to have to pay to be shown properties known only to agents in further away areas. That's one reason why I would think it is on your contract.
If it isn't.. something doesn't sound right. I would walk into any other real estate office and ask to see their version of the form.
Did you really mean to agree to a Represent Buyer contract, and pay a fee, when most people don't?