What are my chances of being able to conceive again?

I have had 3 miscarriages in the last 21/2 yrs. After i had my son when he was 4 months old i became pregnant and had an abortion. The second one wasn't really a miscarriage it was a tubal pregnancy they had to do a d&c. 6 months after that i had another miscarriage at 7 weeks. I found out i was pregnant a couple of weeks ago and yesterday i started bleeding so what are my chances of becoming pregnant again because i really want a second child. will the lining of my uterus start to thin out to the point it can't carry a baby to term? im really scared now pls help.