Feeling scared

Let me start off by explaining that my (then)boyfriend and I got pregnant (surprise) extremely young. I had horrible morning sickness that lasted for most of my pregnancy followed by crippling back pain thanks to my darling babys favorite position (my sciatica) coupled with an anterior placenta which led to my being able to feel almost no movement throughout my pregnancy. We were young and in college living in the dorms and both working part time. We'd gotten engaged a week before discovering our son was gestating. We were terrified he would be our rainbow baby (though we didnt know the term) we'd lost a baby to an early miscarriage the November before. Skip forward, we both have jobs our amazing kiddo is two and early Dec. of 2015 we find out we're expecting again. I was just month amd a half along and helping my best friend labor away to birth he daughter when I started bleeding. Now its 2017 and have decided to TTC for the first time and instead of joy and excitement Im filled with terror. What if we cant conceive another healthy baby.. My (now) husband is over the moon always sure this last bd did the trick encouraging me to buy maternity clothes (which I never got before, lol too broke) and think of baby names but im afraid. Ive been tracking my bbt and CM and neither has changed much in a week and a half... Am I going crazy??