3 weeks on MFP and gained 1 pound

you won't be logging accurately. weigh your food and try doing more exercise

Possibilities include water weight from the increased exercise or hormones (are you nearing your TOM?) or you're eating more than you realize and burning less than you think.

How accurately are you logging (a food scale would be ideal)?

Are you eating back any of your earned exercise calories? If so, how are you estimating your burn?

Would you be comfortable opening your diary for us? You can do this by going to Settings at the top of the page. Then choose Diary Setting and Public and then Save Changes.

I think the telling part of this is "I have only went over a couple of times, maybe 3".
Doestn seem like a good grasp on what is going into the body.

Simply going over isnt terrible, it is how much and how often.

I go over some times, but it isnt much and still considerably less than before I was even trying.

Take in less calories and burn the rest by exercise.

How often do you weigh yourself? How accurately are you logging?

If your data is unreliable, your results will be too.

I am not a fan of weighing once a week, simply because there's a lot of error. My last 3 Sunday weights were:

Week 1: 166.98
Week 2: 167.86 (up 0.88 lbs)
Week 3: 169.40 (up 1.54 lbs)
Total: UP 2.42 lbs

My Last 3 weekly averages were:
Week 1: 169.62
Week 2: 169.54 (down 0.08)
Week 3: 168.61 (down 0.93)
Total: DOWN 1.01 lbs

That's a difference in almost 3.5 pounds! The point I am making is that "gaining a pound" on the scale means nothing if you only have 3 measurements. During the same period of time, just having three measurements made it look like I gained weight... when using 21 measurements showed that my weight was really heading down.

That's just error possibilities with the scale fluctuations. If you're not accurately logging every bit of food, you have no idea how many calories you really are eating.

Basically, assuming you're eating as much as you think you are and burning as much as you think you do, I would change nothing for at least a few more weeks. Give the scale time to reflect what's really happening. I've never seen my scale weight go up (when I was losing) 4 Sundays in a row -- or 4 of any other day of the week for that matter. It takes time for results to start showing up unless you're collecting a lot of data in a consistent manner and are crunching the numbers to tease out what is really happening.


Edit: If you look at my Sunday weights and my weekly averages, you can see that the first two weeks were abnormally low days for me. They were well under my average weight. But, unless I was weighing every day, I would have no way to know that. The third Sunday is slightly above my average weight that week, but not by a huge amount. I've logged almost 26 full weeks of data and can see this pattern for almost every day of the week (Wednesday tends to be my most reliable day). More weights are better than fewer weights when it comes to determining if you are losing or gaining weight over time.

Walmart, Target, etc. type stores will have simple food scales. Also Amazon. Its not a major expense.

Weighing is so important. Even though many food items have info like '1 serving = 1/2 cup' its not necessarily the same as what fits in a measuring cup. Most foods have servings in terms of grams or ounces and that makes it pretty simple with a scale.

Beyond that, give it time. Its not unheard of to take 4-6 weeks to see a result on the scale. Hormones, stress, water weight, etc. can all affect the scale # but in time it will move down if you increase your activity and eat in a reduced calorie range. (Note: reduced but still nutritious. Don't try to cut your calories too sharply as your body needs fuel.)

I exercise 4 times a week doing cardio for 30 mins and take the stairs every chance I get.

Have you used a measuring tape to measure waist, hips, thighs? If you've added all this exercise, I'm guessing you have gained muscle. Congratulations! And, as someone else said, you've started a very healthy exercise habit.