The frustration with breeding! I was there just a couple of months ago. I helped my two with their breeding. He had bred before but she had not. I actually put my hand underneath her and pushed her vagina back. He eventually was able to penetrate her and the tie was on! Our tie lasted about 20 minutes. I held them close together because I didn't want her to pull away from him and hurt his penis.
We had 4 female pups born April 29th.
Good luck!