Help!!!! Please

So I'm TTC I followed the app and did my homework on my fertil days my period was supposed to be 2/1 and usually I get cramps two weeks prior wich I haven't had and no spotting at all my boobs are swollen and they feel a lil hard. I've been feeling nauseous when I'm eating I feel like if I'm going to vomit. 
I don't know what's wrong with me my period is usually on time and I did a pregnancy test and came out negative. 
Any advice???