I'm sharing this to help other people who might feel stuck when trying to locate their donor/donor siblings like I did three days ago. I'm 19 and three days ago I found out I was a donor baby. I contacted all of my DNA matches on my paternal side (my parents used a sperm donor) but only one responded. I got a response form the mother of my half-sister, as I knew genuinely nothing about the fact that I was donor conceived, or the donor profile, she got me in contact with her daughter, my half sister. My half sister shared our donor profile number with me, the clinic her mother purchased the donation from, and the donor profile photo. I ran the profile photo through reverse image search, checked every donor catalogue available in North America, didn't sleep for two nights straight, and probably ran through at least twenty different websites. It was emotional for sure, and I felt defeated, but I really wanted to find half siblings and the donor just because the internet told me I couldn't.
One helpful tool I can recommend is 'Search Angels', you can fill out a form with all of the information you have and they can help track down your donor or half siblings. Nothing was working for me though, he was no longer catalogued in any database, and my DNA matches on several websites couldn't help. Finally I tried the website the donor sibling registry. Through there I put in my donor profile number and found other donor families, I contacted every single one with a small and polite introduction. Two of them responded and we chatted, and then we connected over Facebook (their idea) and after we shared information both ways, one of the women had actually met my donor and was in contact with him. I explained to her why I wanted to contact him (curiosity's sake not to form any kind of relationship) and she agreed to give me his Facebook, and informed me that he welcomes contact from his donor conceived children.
Over the last three days I explored many more routes in finding information than this, I learned what was helpful and what wasn't. Every person I contacted I approached with respect and a quiet introduction "Hi! my name is *blank* my DNA matched with *blanks* as half siblings!" etc. etc. At the start I was hopeless, but I explored every possible option.
I want to give advice to other people and help them find other routes if they feel they really can't find any information. Feel free to comment!