Domain transfer made site look different

I just purchased my domain from GOdaddy, and template from WordPress.com then had it mapped via WordPress. I followed the directions and it seems to have mapped just fine.

I have been building my website for a few days now and was very happy with the appearance. After I paid for the mapping and the template, (theyumblog), my site looks totally different especially on mobile.

I’m very upset and frustrated as to why the appearance changed at all. The background, fonts, photo defaults are all
Different…. In the process it even lost some data. Is this normal? And how can I fix this?