TTC 6 months

Hi ladies, i'm 21 and my partner is 24. We have been together 16 months and bd without any protections or pills since then but never get bfp. Since june this yr we really start ttc like calculate O day etc. This month im 3 days late and start feel sick at 8 dpo but tested at 5 dpo it was bfn. I did have spotting 2-3 days after O. Sometimes feel nausea with food smell, headache and back pain. Should i retest now or wait till a week later to be sure? (sr for the long post?