From what you’re saying it sounds as if he is still very committed to you, and that his changes in behaviour are more than likely coming from the stress that you say he is dealing with outside of the relationship. To be honest, he probably needs you more than ever, but you of course have your needs as well, and if there is anything that makes you feel insecure and anxious, which there seems to be, it would be good to communicate that to your boyfriend.
If anxiety if a genuine problem for you, your boyfriend should be there to help you – you should not feel the need to hide it from him for fear of his reaction. Especially seeing as you seem to be very caring and thoughtful of his personal issues. Maybe easing him in to a conversation about it would be better?