boxer pregnancy

Question
My boxer mated June the 15 n 17 she started gaining weight swelling nipples. We had a family n emergency n hadda be gone for two days when we got back she had lost weight n her nipples r sagging n looks like they have milk n  her valva is swelled..I've felt her belly but not feeling anything is there a chance she miscarried while we were gone. What would be the signs of miscarriage

Answer
This is not enough information to answer this for you.

Was her pregnancy confirmed by a vet? You cannot always feel movement in 30 days.

Swelling of breast and vulva are normally if pregnant. Take her to your vet if you feel something is wrong. Miscarrying usually has visual signs; bleeding, discharge, lethargy, licking, etc.