"...Tonight one of my neighbours asked me if I am pregnant. I laughed it off and said no, just eating too much food, but I feel on the verge of tears. Yes I know they are a rude, but I know that it does appear that way..."
OP, if you feel it preserves your dignity to laugh it off, then by all means do so, but you know you don't have to, right?
It is extremely rude to comment upon a woman's body or query her reproductive status without invitation.
Women can appear to have varyingly distended abdomens for all manner of reasons - GIT disorders or other medical issues, menstrual cycle stuff, being overweight, even just having a large meal or an unflattering outfit.
Some women may actually be pregnant, or have recently miscarried, and not only don't owe their fucking nosy neighbour information in either case, shouldn't have to suffer the awkwardness of refusing the pressure to give that private information.
Your neighbour and anyone else who makes these comments would have to have been living under a rock their entire life to not know that women don't like being queried about being pregnant or to be told they look pregnant when any one of those reasons is in play - that it's embarrassing and/or makes them feel awkward and self-conscious.
Therefore, anyone who makes such comments is either being thoughtlessly rude, or they are wilfully putting their curiosity above good manners and your comfort.
...In either case, you should not go out of your way to protect them from the consequences of their rudeness by hiding your reaction, unless it makes you feel better to do so.
Too often women are expected to laugh it off and hide their irritation, shock, anger or hurt when others make rude/intrusive/entitled/ demeaning/objectifying/insulting comments about their body, appearance or reproductive status.
...To just absorb the awkwardness internally in order to spare a rude, entitled or thoughtless person's feelings when they gave no weight whatsoever to hers.
Perhaps if those people experienced the cut or a verbal lashing more often in response to their rude, intrusive behaviour, they'd think twice about their perceived entitlement to comment upon women's bodies so freely.