16 and possibly pregnant

me and my boyfriend have been together for a long time, and we're obviously having sex (we don't use condoms). i've been having some "signs" if you'll call them, in the past 3 or 4 weeks. for example: spotting (about 2 weeks ago), very little motivation to do anything (i'm generally a hyper teenager, i always have to be doing something), weird cravings for food i don't even like (fish, seafood, etc.), crazy mood swings (my boyfriend and family have begun to notice them in tha past 2 or 3 weeks), breaking out on my back (i normally have clear skin, and if i do have a breakout it's on my face), i've gotten sick twice (once in the morning, and once after eating lunch at school), i use the restroom at least 12 times at school, smoking a cigarette makes me feel sick to my stomach and usually end up putting it out half way, i'm very emotional. there's a few more, but i can't recall them off the top of my head. i took a home test and it came out negative. but my friend told me she took 4 when she suspected she was pregnant, the first 3 being negative.
it would be really nice for a few words of advice, or just someone to talk to.