What am I doing wrong because I've only lost 13lbs at 2 months post-op?

Each process is different and not all patients have a massive weight loss in the first months. for what you write you are taking your process to the letter.If you feel that you are having a slow process consult your nutritionist or main surgeon to assist you and can give you guidance to improve.To maintain a positive mind: 1. Remember your goal, what is your objective. 2. Never look back, fresh start when needed it 3. Small Goals. Just live day by day. TODAY I'LL DO MY TRAIN ROUTINE. TODAY I'LL EAT HEALTHY. 4. Look for support groups. Its known that you'll have better results.
Here are a few quick tips.
1.Try to avoid artificial sweeteners. Artificial sweeteners can be 300x (if not more) sweeteners than real sugar.
2.Rest. When the body is tired it looks for energy (it is trying to do us a favor) and it knows the the quickest way for energy to get into the body is via sugar. Ever notice that when you are tired you crave processed carbs and/or sweets? This is why. The next time you feel like you need to rest, do yourself a favor and rest.
3. Add more natural sweet food. This one is especially true for my dieters and low carb peeps. When we have a diet very low in carbohydrates and sugar we tend to want sweets. By simply adding some nutritious sweet foods to your day you can cut that craving way back. Some great examples are sweet potatoes, squash, brown rice, oats, and carrots. An idea of a yummy snack might be carob chips and coconut with nuts mix.
4. Protein. If you find yourself craving sugar, just take note of how much protein you have been eating. If it seems high, try cutting back. If it seems low, experiment with adding some more in. I’m telling you, being interested in ourselves is one of the best ways to figure out what our bodies need.
5. Add non-food sweetness. It can be a simple as a phone call with a dear friend, a walk, a girls night out, a great book, etc. The options are endless, but the key component is that you remember to keep yourself on the top of your own list.Don't be discouraged ,

Hi, I would recommend having a little patience. This procedure helps in a longer time frame, so if some weeks you loose less than others it´s probably not that significant.
Just keep tracking your calories and you will be fine.