burning during sex

So a little about me to get an understanding of what my sex life is ussually like. I have been married for three years and that's when i lost my virginity. I can have clitoral orgasms, as many as 3-4 in one setting. I am ussually dry down there no matter how much foreplay we have and even after orgasms so penetration without lube is not an option. Penetration has always been painful for me i was even diagnosed with vaginismus by a physical therapist who taught me some excercises that would help a bit. The pain would be at the begining then become tolerable. I just had my first baby and am breastfeeding. Penetration now burns so so much and it lasts throughout the whole process. There is no discharge or itchiness so i don't think i have a yeast infection and we did use lube but it still burned really bad. I took a look down there for any cuts, i couldn't see any but my vulva was bright red. We tried again 2 days later and it still really burned. Help, i feel hopeless as "penetration" is always such an ordeal for me and i just want to go back to pain on entering but not throughout the whole process.