So... at the risk of giving too much away on the internet, but in the hope that I can help someone else, I'll provide a response....
I can relate to a lot of these things from past experiences. Personally, I have OCD and have been takings meds long term for it. I've had the harm OCD in the past (not fun), but that went away and the OCD instead focused on other things (also not fun). I've had a couple of rounds of CBT, one on the NHS (not great) and one private (excellent). The OCD is 98% better / managed now, but unfortunately will probably always be there in the background. The vast majority of the time I am on form, feeling 100% "normal"; however I might have a couple of brief episodes in a year which knock me for six for a couple of days. Usually due to a heavy night on the booze or serious lack of sleep the previous night. I can usually get these under control quickly using techniques learnt through therapy.
In terms of the harm OCD (if you have OCD - please get a proper diagnosis, there's no way we can tell you either way) it's basically a specific manifestation of what is a very adaptable disease, OCD. You need to remember that OCD attacks whatever is most special to you. The thoughts are ego-dystonic - an OCD sufferer will never act them out, that's why they are so distressing (See -
https://ocdla.com/harm-ocd-1-1982). I strongly suggest you seek the advice of a Doctor and ask for a referral to a proper psychotherapist for a definitive diagnosis. Self diagnosing is never a good thing. Counselling may help in the short term, but will do you no good in the long term if you do have a proper OCD diagnosis. OCD requires a fairly specific type of treatment called Exposure and Response Prevention, which is often combined with some form of mindfulness therapy. Counselling generally provides reassurance and a place to vent, which gives short term relief, but is pretty much the exact opposite of ERP and can actually be harmful if it feeds a cycle of reassurance and avoidance. Too tackle it properly, you need to speak to someone with the appropriate training / qualifications / experience.
I was diagnosed ~10 years ago and even since then there has been a huge increase in awareness of the condition and there is a load of info on line. It is estimated that ~2% of the population suffer from it to a clinically significant level. I wouldn't worry too much about the social getting involved if you visit the doctor as I'm sure they have heard it all before. It's probably best to get yourself in for a check up / referral sooner rather than later, so you can start tackling any issue you may have. In my humble opinion, if you can afford private, go for it - the waiting time for me on the NHS in ~2007 was >12months, so is probably even longer now. Treatment takes some time and you need to prepare for relapses, but it definitely does make you stronger in the long run in other aspects of life. My NHS treatment was not great, partly because the therapist was clueless on OCD and partly because I wasn't completely open with her as it was all a bit too disturbing / embarrassing. This led to me being given a generalised anxiety disorder diagnosis early on, which is treated in a slightly different way. I only got the OCD diagnosis very close to the end of exhausting all my NHS allotted sessions, at which point they said goodbye and good luck. The next time, a couple of years later I was completely open with the private therapist and she didn't even flinch. "Seen it all before and worse", she said.
In terms of your partner - yeah I can vouch that it freaks them out at the start, but if you involve them (within reason) and help to educate them on what is a horrible and weird disease then they will likely become a huge help and you can become closer through it. It's a bit of a running joke for us - the partner shouldn't really provide reassurance at all, you're supposed to work it through yourself, so mine doesn't. She's pretty brutal about it sometimes.
If I can recommend a book to read to give you some insight, try this:
https://www.amazon.fr/Brain-Lock-Yourself-Obsessive-Compulsive-Behavior/dp/0060987111
I was in a very bad place at one point and when I read this book I almost felt instantly better as it gave me the hope and motivation to tackle the condition head on. It is a ******* ballache, but you can get through it.
EDIT: If I can provide one final piece of advice - stay off the specially made mental health forums. They don't help. They basically just provide a feedback loop for everyone's suffering and amplify the problems.