Welcome!
Right off the top I see you have a self-inflicted wound. You installed CleanMyMac.
You paid Apple a lot of money to include automatic maintenance routines in the OS that, every day in the early morning hours. fire up to do any needed cleaning, defragging, and other maintenance with your needing to do anything. When you put a third-party "cleaner" on top of that, you get conflicts and things get sloppy.
Completely remove CMM using the included uninstaller or the instructions on the company's support site.
That said, your MBP shipped with a slower hard drive than it is capable of driving. Many did, including my 2012 13-inch. Slow booting and app launching are the result. Adding RAM which, in your case, is a good idea anyway, won't fix the slow booting. Only a faster drive will, preferable a solid state drive (SSD). The prices on SSDs have fallen so much that I see no need to shop for a conventional drive any more
Let's look at your drive scores:
Performance:
System Load: 1.88 (1 min ago) 1.69 (5 min ago) 1.65 (15 min ago)
Nominal I/O speed: 0.06 MB/s
File system: 120.02 seconds (timed out) ⬅️
Write speed: 38 MB/s
Read speed: 59 MB/s
I installed an inexpensive OWC SSD in my 2012 MBP and the write/read scores are now about 500MB and the computer is as fast as many new ones.
Another issue that I've indicated with the ⬅️ icon is that fact that the test timed out. Based on similar reports, that could indicate a worn hard drive cable. That MBP design has a tendency to cause cable wear over time, like 3-6 years. The good new is that the cabe is cheap (~US$15), available (here), and easy to install without professional help. Best practice is to change the HD cable a the same you change the drive.
You can install 500GB SSD and a ne cable for about US$120 and do it yourelf. Increasing RAM from the current 4GB to a more reasonable 8GB is about $45. We can't do the cost justification for you.
