Two is when kids start to develop a sense of themselves separate from other people. It's when they start to realize that they have some control over their world,a nd they set out to see just how far that control extends. A certain amount of so-called rebellion and stubbornness is to be expected.
He's also under a lot of stress for a little guy - cut him some slack. He has had several major upheavals to his world, all very close together, and with no time to really adjust to one before another hit. I'm 43, and if I had moved to a place where I knew nobody, not had the chance for the company of people my own age, had a stranger come into my life (even a nice one) and start taking up large portions of my time with the only person I did know, and had the household rules change on me, all within the space of a month, I'd be curled up in a corner sucking my thumb.
How long have you and his dad been separated/divorced? Did he see his dad a lot before you moved? Part of the problem may be simply that he misses his dad.
He went form being around other kids every day to just being with you. He needs the company of other kids, not just adults.
When you started dating, he went from having you all to himslef to having to sahre you with someone else. Even if he likes your boyfriend, it's still a tough adjustment for him to make.
Did you insist that he say sir/ma'am before starting to date this guy? If not, he may see the new guy as having come in and chganged all the rules, and he may resent it. And quite frankly, your boyfriend should not be trying to parent him. He may be clamming up because refusing to answer is one of the few ways that he feels like he has any control over anything.
A two-hour nap is pretty long. If he sleeps more than that during the day, he's not going to sleep at night.
Perhaps he's getting cranky before dinner because he's hungry. Children's appetites change as they grow. His metabolism is faster than yours and his stomach capacity is smaller, so it's really not reasonable to expect him to keep to a meal schedule that is designed for adults. Have you tried feeding him his supper instead of a snack when he wakes from his nap, and then letting him have a snack later if he gets hungry again?
The hormone shifts in early pregnancy make us more emotional than normal, and it's not uncommon to over-react to small annoyances as though they were earth-shattering catastrophes. I don't know about you, but I was also constantly exhausted when I was pregnant. Are you taking proper care of yourself? Eating nutritious meals? Getting enough sleep? Try napping when he naps. You might find that his moods will improve if you're not as tired - his crankiness could be partly a response to your own.