I recently bought my first real watch, a 1984 speedmaster professional. I went to a reputable walk-in store because I am experienced and wanted to buy from a trusted source. I love the watch but have been trying to do some research and now have some questions:

It was sold as 1984 but now I’m not so sure. The serial number is 48371xxx. Looking at some pictures on the net, the dial looks more mid-90s? There were no original papers but the receipt mentions case back #345.0022. I have seen 145.0022, but what does 345.0022 mean, and where is it found on the watch? I have not seen the movement (should I have asked to see it before I bought?).

The bracelet has 842. Is this consistent with an 84 or 90s? Appreciate any info you can give me - I'm hoping that, at least, all the parts are original and consistent
Thanks all