heat cycle/duration

Question
I have a 1/2 Chocolate Lab, 1/2 Chesapeak Bay retriever female;
How often should she come in heat, and how long will the cycle last?
She came in heat around the middle of June and lasted a couple weeks. Now she has come in heat again around 7/17, (one month apart)
Last year it was June and again after 1st of year around mid January. This year she is different cycle.

Answer
Most dogs come in heat about every 6 months and discharge for 2-3 weeks and take several more weeks for all the swelling and everything to return to normal.  Sometimes they will start to discharge, and then stop, and start again before long.  That is what you may have seen.  Infections can also cause discharges.  If you see more of it, you may want to have a vet check her.  The second and third weeks are when the most risk of accidental breeding is. Don't take this lightly. She will do anything to get loose and get to a male. Once loose, an accidental breeding and an unwanted litter is far from the worst that can happen. Such breedings can also result in fatal infections. She can get killed when she dashes heedlessly across the road in front of a car. Other dogs or coyotes may kill her.

You can expect the same thing about every 6 months for the rest of her life if you don't go ahead and get her spayed. There is no other answer, and no good reason not to. Besides saving the hassles, it reduces the chances of cancer later in life. Please make life easier for yourself, her, and society in general by getting her spayed as soon as a vet will do it.  There is no good reason to keep an intact mixed breed.