HELP,

I am totally baffled and hope someone maybe able to help me with my border collie bitch!
I hope you don't mind me contacting to you, however I am a bit worried about my Border collie. I saw that you breed Borders and my Bitch is ex working (because she loved her cuddles more than chasing sheep, so I rescued her) She is around 2 and a bit years old now, and we have had her around 7 months. She has had one season with us in December and we had put her out to stud as she is an amazing girl (bet most owners say that) and there is nothing I wouldn't do for her. She was mated with another Border that looks like her twin! Although we were told he was only 12 months, we didn’t believe it, and so asked our vets opinion that told us he was only 6 months (even though he is quite a big boy). The mating took place about 2 times confirmed ties last around 15 mins each.
She hasn't put on any weight on however she is still swollen like she is still in season! She would have been due 2 weeks ago but we had our vet look at her and she had an ultra sound, which showed nothing at all. Her teats are also rather large, however they have always been like that when she came. Now she is being a flirt with our other collie again, and he has been trying to mount her, Proper persistent with it, and he cries when she isn't in the room the whole issue that she would have had should she be ready after another season, however its still very early since the last one being in December. Would it have been possible for her to have another season now? Or even still be in season? As I can’t work it out at all. If you could shed any light on this I would be very grateful.
Thanks Peeps