Bleeding after intercourse -4 month post partum tmi

[hartmel]

It is now 4 month since I gave birth to my second child. I'm breastfeeding her. But after me and DH make love I'm starting bleed. I had second degree tear. With both kids But didn't had that problem with my first. It is not heavy bleeding very light but I get period like cramps and it usually last for 3-4 days. I had mentioned it to my Gp but all she said is because I'm breastfeeding I don't get a normal period. And she said it is normal. I don't think that it is normal after having sex to bleed (and no my DH is not rough he is very gentle because he knows that my stitches still hurt)
Also my cervix is still very low and open..

I'm worried I might me something bad.. Or am I overreacting