If you're like me and tend to takes risks I would do the following:
1. I take a full scan had been already done by you. If you like go into bitdefender settings and see if heuristic analysis get be set to high indepth analysis. Note I use Kaspersky.
2. Download and install Malwarebytes, update and scan, if you have issue installing it then download RKILL and run that and leave it running then install malwarebytes, as this application stops active viruses etc that prevent installation of antivirus software etc, now scan your pc and see the results and quarantine.
3. Download RogueKiller and do the same.
4. Download Unhackme and use the 30 days trial and see what interesting info this application kicks up. It also safe mode check and online virustotal check.
5. If you are using anything other than windows 10 then now download Combofix, which is an excellent piece of software which will search and remove stubborn and highly dangerous and well written malware infections. Most IT-Gurus will tell you not to run this software unless advised so this is where I take the risk and I have no issues using Combofix. It will do a integrity check of windows files, checks for viruses and removes any infections and restores windows to its original state.
NB: Before using combofix, back up your files to a separate clean hard drive, and if you followed steps 1 to 4 chances are its safe to backup files. If you have a lot of legally bought software, then download License Crawler and run that to find any serial keys and back up that and finally run Combofix which will take a long time and usually fixes big issues.