Boston Terrier Pregnant without Tie?

by Jenn
(Ohio, US)

I have a 2 year old female boston and this is the 2nd time I have tried to breed her with a very handsome smaller male (he is proven) I have taken her to him 3 times so far and I know he has penetrated her but they have not tied. Is it possible for her to still become pregnant even if they do not tie?