Hi there my bitch was mated 8.5 weeks ago but all the signs look like she is not pregnant.. (nothing to be seen on the scan and also she hasn't grown in size at all) we have had a litter from her 3yrs ago, then tryed for a litter last sept with 2 successful matings but sadly no pregnancy and then this year again 2 good matings and for what it seems no pups she would have be due at the weekend......... She has started to have a watery bloody discharge  and has swolen up a little on her bits.  She seems fine in herself and throughout this whole time has not changed her behaviour at all running around with the other dogs without getting tired out and not hiding herself away like she did last time.
What do you think is going on with her? has anyone had this with their bitch before
any help appreciated

many thanks