Breast Milk?.

I'm 16 weeks and 6 days so almost 17 weeks. Well today my breast were hurting and I started to rub them to see if that would help and then I saw some clear liquid coming out. It wasn't a lot at first but now even some pressure it will leak out like a lot. I'm just curious if this is normal and what exactly is this? I know the yellowish creamy is colostrum and of course the white is actual milk but what is this? Thanks in advance.