I have a 4 1/2 month old male Boston and a 1 year old female Boston. My female had her first heat about 4 weeks ago. Her tits are bigger and swollen. And she is still swollen. Is she pregnant? The dogs are inside dogs and they play outside in our fenced in back yard. I haven't seen any other dogs around. We let our male stay around her when she was in heat because we thought he was too young to get her pregnant. Were we wrong?