No you are not alone. It can be hard to reach out for support. I find it especially hard to reach out for support in the academic or work setting where I want to be seen as productive and hard-working and efficient and I am worried and concerned about showing that I am struggling. I am also quite an independent person so that doesn't help. And of course there is the huge worry that people won't understand and then also the worry about how to best communicate what I am struggling with. And it is impossible to predict the reaction of individual people. However from what you say your company sounds supportive and not admitting you are struggling is also not ideal- at least for me it meant that it was slowly eating away at me, I was worried that I was not at my best and I tried even harder and ultimately that contributed to getting more overwhelmed and burntout etc. I did actually tell my manager that I was autistic but I didn't get support, only the 'oh everyone is a little autistic' . I might have been unlucky. And I didn't go about it in a good way because I didn't really understand myself what adjustments could have helped me. I have now left that job as I didn't like it anyways and I am starting a PhD but this time I am trying to be more vocal though still struggling with that. I am a people pleaser too (it's one of my masking strategies) so I find it very hard to vocalise my needs and to stand up for myself- but this comes at a huge cost to yourself... and is in the long term not sustainable.
It can be a huge relief though when you do reach out for support- that could be a way to motivate yourself? And if you don't tell it will be an added worry that you have to 'hide that you are struggling' which takes more energy that would be better spent on other things. I told my university now that I am autistic and they are putting in a lot of support so I am very glad that I told them. I am still struggling to communicate my needs with my supervisor but I am getting a bit better and I did manage to say I need a break before starting. I find it quite hard to talk about possible struggles as I am only just starting. The advantage you have is that they already know you and value your work. Ultimately it is in everyone's best interest that you are supported as best as possible so that you can feel good and be productive. I am not so sure how to motivate yourself to get going or to make the call.... but it does sound like the anonymous phone service could be a great starting point? There is no risk at all in that and that way you could gather more information so that you can plan how to proceed. More information is usually good.
Also, I just want to say that I think you are already a good part of the way there in terms of asking for help. You've acknowledged that you are struggling and could benefit from some support, you've tried reaching out, though in quite indirect ways, you've realised that you might need to be clearer for your cries for help to be recognised, you've identified possible actions you could take (like call the helpline) and you are trying to somehow find the motivation to put your plan into action (so that shows that you must think that it would be a good idea to do so). So really you are almost there- it might feel like a huge hurdle to make that call. But also give yourself credit for already getting this far. I'm almost certain that you will make that call.
Also, I just want to say that I think you are already a good part of the way there in terms of asking for help. You've acknowledged that you are struggling and could benefit from some support, you've tried reaching out, though in quite indirect ways, you've realised that you might need to be clearer for your cries for help to be recognised, you've identified possible actions you could take (like call the helpline) and you are trying to somehow find the motivation to put your plan into action (so that shows that you must think that it would be a good idea to do so). So really you are almost there- it might feel like a huge hurdle to make that call. But also give yourself credit for already getting this far. I'm almost certain that you will make that call.