Smoking cigarettes and Our Fertility!

K • momma bear and wifey ;)
Me and hubby have been ttc for 4 months. I'm 21 and he's 22. We are actually shocked I didn't get pregnant these past 2 months because we have BD on every day in fertile window and I'm taking prenatals and drinking mainly water. We're young and my fertility is supposed to be at its peak! 
We are Both heavy smokers, though. I know once I concieve, I have to stop anyway. But I didn't think I would have to quit to concieve.
I've cut back a lot but I guess not enough. Any tips or advice??
Thanks :) 💋