It's too early to say for sure, but it's possible this may be part due to implantation bleeding. However since you are both trying and if you are really wanting to be pregnant, this can actually throw off your cycle or stress as you indicated.
Go ahead and try and relax and don't think of being pregnant or anything at this point and see if you end up starting a regular flow or not.
I don't know how long you have been trying etc., but you may want to get an ovulation kit to find out when you are ovulating , therefore you can have sex during the right time of the month and have a greater chance. Even though it's hard, do try to relax and stay stress free.
Best of luck Hun, Hope this helps, If you need anything else please feel free to ask. If you found this helpful don’t forget to click the *ACCEPT* button and leave *POSITIVE* feedback.