This is quite a reasonable question. Strictly speaking, your best bet to answer it would have been to freeze your system and to perform forensic tests. Any later intervention on your part, including virus removal, will alter and possibly erase altogether any bread crumb left behind by your intruder.
Given that this path is no longer open to you, the best thing is to use a Vulnerability Scanner, a program i.e. designed exactly in order to stress-test your installation. There are very may, you may just Google the term Vulnerability Scanner, but by far the best known is Nessus. It comes in several version, from free to paid with different licenses, and it can become quite expensive, possibly more than you are willing to fork out.
However, there is also a free version of it, which comes pre-installed on Kali Linux. You will have to register it, even though it is completely free. Many of us use Kali by installing it onto a VM on a laptop, then performing the stress-tests from outside our homes, to see which defects (=non-patched, known vulnerabilities, most often) are left on the applications running on an Internet-facing server.
There are guides teaching you how to use that all over the Internet, and you can try it also within your own LAN (if you trust your firewall), and even from within the same pc, if you will be running Kali as a VM.