According to Islam, should I take the Shahadah even though I have some doubts regarding the prophethood?

I am an agnostic who has come to learn about Islam, and I now believe in one God. I also think that Muhammad could have been a prophet, but I still have a few doubts about this. I would say I am about 60% sure that he is. Should I hold off on taking my shahada? I also don't know how strictly I would adhere to the rulings until I am completely convinced but I feel as if I will never know for certain, as I have a nature to doubt.