cycle day 45 no period, negative hcg

Hi ladies.... just looking for some help and advice. I am TTC #1. My husband and I have been trying for 4 months. I am 31. Previously I was on birth control for 12 years. My first three cycles were all 31 days long with showing positive opk on days 18 or 19. Currently I am on cycle day 45 and I got a positive opk on day 25. I have not started my period but I've had bloating, lower back pain, and cramping on and off for the last two weeks. Even with calculating the late ovulation I'm a week late and have been getting all negative pregnancy tests. Has this happened to anyone else? If I'm not pregnant I just want my period to start so I can have a new month to try.