It doesn't mean you'll show early, it means you'll probably look chubbier all over unfortunately.
I'm not judging you because I've definitely been hitting the snacks lots more than before I was pregnant. I just feel hungry a lot of the time, and use snacks to ward off the nausea and give my energy when I'm tired.
Unfortunately as well, I have gone off all my favourite healthy foods. I can't remember the last time I ate a salad, the thought makes me gagg and I am craving mostly salty and carby foods.
If you're eating out of nerves then this might help to reassure you - I check it almost every day and it makes me feel loads better - datayze.com/miscarriage-reassurer.php
Porridge with fruit is a really filling and slow release breakfast (I have it for dinner sometimes if i can't stomach anything more than that).
Other things to snack on are popcorn, rice cakes, etc. I'm obsessed with Salt & Vinegar snackajacks. I'm certainly indulging in things I fancy but I also don't want to use it as an excuse to binge on junk for 9 months.
Remember that a) you should be giving your growing baby the nutrients it needs to develop, not junk food that will provide little nourishment and b) you will have to lose the weight after, so don't make it harder for yourself now
If you're overeating but only on sensible foods, then I think you can put that down to needing the extra energy to grow a person. Don't feel too bad about being hungrier than usual.
Are you drinking lots of water? Hunger is usually dehydration. I'm trying to drink lots of no added sugar squash and herbal teas.
Re exercise, I wouldn't go starting something new, but stick to what you were already doing before. If that's nothing, then you can always take long walks. I try to do at least 30 mins a day, even if its just a brisk walk. Just do what you can and don't be too hard on yourself.
The book "How to grow a baby and push it out" says that we only need to consume 200 more calories per day, and that's not until the 3rd trimester.
Hope this helps! Good luck with your pregnancy :)