B737 First Officer reported that due to multiple distractions and delays the Final Hazmat goods message from the flight crew to Dispatch was not sent to Dispatch prior to brake release. The message was submitted during pushback.

Narrative

Initial Hazardous goods ACARS message was printed; clipped onto the CA (Captain) yoke; and identified to the CA. CA said he needed to send the message after we had received the final Hazardous goods message; Final message was identified; printed out; and clipped onto the CA yoke. During this time I noticed we had numerous baggage carts lined up and sealed on the FO (First Officer) side of the aircraft with zero ramp personnel about 15 minutes prior to departure. For the next 40+ minutes the CA and I tried to coordinate with Operations; Ramp; and Dispatch over comm 1; 2 and ACARs to resolve the situation and delay. I could not see a single sole on the ramp and we asked Ramp if we were on a ramp hold for lightning. They said no. When we finally got a hold of Operations they notified us that 50+ ramp personnel had called out of work and they had no idea when we might have our bags loaded. The CA did a good job coordinating with the flight attendants and passengers through the delay. This was of concern as Severe thunderstorms were building along our route and in the vicinity of ZZZ and the weather in ZZZ1 as far as low ceilings was getting worse with 21 planes in lineup for takeoff and growing. We then coordinated with Dispatch to let them know about our delay. The bags were finally loaded; the baggage doors closed; and the before push checklist was complete. The one item missing was the Dangerous Goods ACARS msg. As soon as the CA coordinated with the push crew and released the parking brake; he looked down and realized the message had not been sent before brake release.