When my two were little babies, I felt the same way. Spending time online didn't help, and in particular, I'd think mumsnet would be one of the worst places to find advice or guidance. Most people posting here also don't have medical degrees, haven't done much research, and are following general NHS advice. Not necessarily incorrectly.
Yes, vaccines save lives. Across populations, they do slow or stop the spread of serious diseases. But they also come with some very real and quite scary risks. Vaccine injuries are widely reported and it would be very misleading to say that all vaccines are always safe - it's just not true.
I spoke to my health visitor, practice nurse and several GPs, requesting the patient information leaflets for the vaccines (these can also often be found online, but generally aren't freely offered to parents at appointments). The risks are real, as are the benefits.
If I were you, I'd get off the Internet and trust your instincts and genuine sources of information - vaccine safety trials, patient information leaflets etc. Vaccine injury is extremely unlikely, but it is a possibility. You need to weigh up if the pros outweigh the cons. For most, they do.
Also consider that some parents opt to delay vaccines or spread them out, and there is medical support for this too.
I hope this perspective helps. I'm fully aware that I'm opening myself up to criticism on this thread (funny how "Pro vaxxers" are often as dogmatic or more so than so called "anti vaxxers"!) But I don't think you, or any parent, is wrong to question a medical decision for your child, especially when it does carry risks, and I don't want you to feel wrong for asking questions. Asking the questions doesn't make you "anti", even if mumsnet disagrees!
This is just what I would have wanted to hear when I had a small baby.