Could be pregnant? Im TTC...help me pls.?

hi everybody.. i do not hv period for last 4 mth and that time im on seriously diet. Doctor said,that is normal because of hormone change and nothing to worry. After married,we have sex for twice per week. My period due date on 28 of june. But on 30 june,i have brown discharge a bit and light red(pink) a bit. Last saturday i feel back pain and i do lot of work (shift to new house). Today, i feel lower stomach pain. Is it im preg? tomoro i want to test...need advice.. is it my lower stomach and backpain because do a lot of work?