how can you tell if my jack russell is pregnant?

Question
hi there i have a female jack russell and she is 14months old, she had a season in november ( just gone )
and a boy jack russell got hold of her in the park but didnt latch on but did try, since then she has been acting really strangley like chewing on wooden table legs and she never chewed as a baby puppy, being sick? dont know if its because shes chewing things, her nipples have grown and look saggy with lumps behind them and she just basically acting different. I was told not to worry about it because they didnt actually lock on so i dont know if its just me worrying or if she could actually be pregnant? could you help? thanks dean

Answer
If they didn't "tie" (lock as you called it) then there is no way she could be pregnant. However, if her nipples are growing, it is a good indication that she may be.  Is there a chance that another dog could have gotten to her without you knowing?
To be sure, you can have a test done at your veterinarians office.
They can take a vaginal smear, a blood test, or do an xray/ultrasound to give you a definitive answer. It's worth the price to ease your mind. While you're there, make an appointment to have her spayed so you don't have to go through this again. If she is pregnant you have lots of learning and planning to do!! I wish you the very best of luck!