I really need some adive, please :(?

I've been with my boyfriend for a year now. Before him I was with my ex for six years. Six years of lying and cheating and fighting. But he was my first love and I thought it was impossible to leave him and be happy. But finally I did! And two months later I met my current boyfriend! We've had the best relationship I could ever imagine and finally in my life I'm treated right! But there seems to be a problem now. I find it extremely hard to trust him! At first it was just fun and new and exciting, but now that I've completely fallen in love with him I find myself having trust issues. I know it's not healthy and I'm scared it will ruin our relationship as you cant have one without trust. I know I mostly feel like this because of what Ive been through. But theres also another reason. When we first got together he had a lock on his phone. Then a few months later he took it off and I never seen it on there again. Then one night while he was in the shower i went through it and he came out and caught me. I didnt get as far as going through his text messages. But he was kind of upset and ever since he's taken his phone with him EVERWHERE he goes. This happened in January and he hasnt left his phone anywhere since. Isn't that a sign he's cheating? I'm also 14 weeks pregnant and very emotional.. do i just sound crazy? Or is the phone thing something to be worried about? I dont want to get hurt again and i would much rather get out of the relationship before it would be more difficult. Any advice please!!