Drinking and smoking until I knew!!!

Sarah • 35 first time mum!
Hi, 
I have recently discovered I am 20 weeks pregnant..... I had no idea. My doctor told me she thought I was just constipated and the reason I hadn't had my period is because I had come off my pill and it takes a while for your body to regulate your cycle again. 
I'm absolutely delighted as I've always wanted to be a mummy.  But I'm worried since I drank quite a lot (5 times a week, I work in the industry) and smoked around 15 a day before I found out. 
Ive stopped now and I'm eating healthily and everything seems to be as it should..... I'm just panicking incase I've done damage to my baby. Anyone else have a similar story???