Feeling sick.

Is it possible to start feeling sick after eating in early stages of pregnancy? I'm extremely nauseous after breakfast and dinner especially. I'm only 7DPO.. I've also been napping more, if I don't get a chance to nap I over sleep my alarm and i don't go to bed late. I'm not sure, we have been trying extra hard this month and added preseed as well. Is it possible to feel like this before implantation or right after ?