You can hope having her fixed will help before long. Spay/neutering is no cure all, but an essential first step. That responsible step may take a little time to act. Long before a female comes in season, their reproductive system is maturing and beginning to produce hormones. That would have been enough to excite your boys. Getting it stopped may take more than fixing her.
The key to most behavior problems is approaching things using the dog's natural instincts. Dogs see all the people and dogs in the household as a pack with each having their own rank in the pack and a top dog. Life is much easier if the 2 legged pack members outrank the 4 legged ones. You can learn to play the role of top dog by reading some books or going to a good obedience class. A good obedience class or book is about you being top dog, not about rewarding standard commands with a treat. Start at Raising Your Dog with the Monks of New Skete
For more on being top dog, see Establishing and Keeping Alpha Position
Once you have your pack properly structured, and her hormones settled down, You will need to do a complete cleaning. I would recommend steam cleaning the carpets using the pet odor enzymes. Clean the hard surface floors with vinegar water.
When you catch one in the act of marking, give it a sharp ''Ut, ut, ut!'' and take it outside. You will need to crate them to keep them from marking when you aren't watching. Other dogs may
Not be as bad as the young Labs I am plagued with. Still your house and dog
Will be much safer with the dog in a crate when you are away. The dog may be
Happier in its den than loose in the house. It relaxes, it feels safe in its
Den. It rests, the body slows down reducing the need for water and relieving
Its self. Dogs that have been crated all along do very well. Many of them
Will rest in their crates even when the door is open. I think the plastic
Ones give the dog more of a safe, enclosed den feeling. They are harder for
Dogs to open too. Metal ones can be put in a corner or covered with
Something the dog can't pull in and chew. Select a crate just big enough for the full grown dog to stretch out in.
Leave it some toys. Perhaps a Kong filled with peanut butter. Don't leave
Anything in the crate the dog might chew up. It will do fine without even any
Bedding. You will come home to a safe dog and a house you can enjoy.
A dog that has not been crated since it was little, make take some work.
Start just putting its toys and treats in the crate. Praise it for going
in. If you have been able to trust it with any bedding, put that in the crate.
Feed it in the crate. This is also an easy way to maintain order at feeding
Time for more than one dog.
Use the crate only when you must I have a short length of chain fastened to
My computer desk. With more mats around the chair mat, this gives a place
Where the puppy is with me, but about as controlled as in the crate, while
Still allowing me to get some work done, or at least answer AskMe questions.