Also, if you're worried about being pregnant from having sex on the 5th of December, I'd say you're okay. Im currently 5 weeks along and that puts my conception around the 20th of December. Granted yes, everyone has different symptoms but it would be more than just weight gain (I've actually been losing weight so far) and frequently having to pee.
Thank you! I'm keeping my fingers crossed that it's just that.
There is some reason to be concerned but it doesn't sound like I would be too worried.
gaining weight could also be the fact that muscle weighs more than fat and you're gaining muscle from working out. If you're still getting your period on time and its an actual period (not just spotting), there doesn't seem like there's too much to worry about.
However, if you'd like to put your mind at ease, grab a hpt and take it one morning.