It seems your DNS records do not include an A record. You need to go to Cloudflare Dashboard > DNS and make sure there is one A record pointing to the IP address of your origin server (hosting provider), and a CNAME record with name “www” and value “tomasoliveira.pt”.
Also, did your website have SSL before adding it to Cloudflare? If not, you must use Flexible for now, then later you can add a Let’s Encrypt or another SSL cert to your origin and upgrade it to Full or Full (strict).