You have no lack of gut bacteria, that much is very safe to say. Everyone has gut bacteria in spades. The gut bacteria that you do have may not be the optimal, but no one even knows what the optimal gut microbiome/microbiota is. The study of the effects of different populations of gut flora is in its infancy. The most intensive studies are being carried out in animal models, and their applicability to humans is not yet guaranteed.
Can a person change their microbiome with probiotics? Researchers are still dubious. There is a lot of research that indicates that the intestinal flora you carry throughout your life is largely determined in early infancy. Others believe that the microbiome changes over time; this has been shown to occur especially due to illness or antibiotic use.
The two areas of greatest study in humans is obesity (associated with certain strains of gut bacteria in certain populations) and as a treatment for Clostridium Difficile colitis, and none of the findings can be generalized yet to the "normal" population. Inflammatory Bowel Disease had been studied as well, and some other disorders, to a lesser extent. But how to change our microbiomes is far from a known fact.
However, what scientists who study the gut microbiome do agree on is that a healthy diet is a better way to cultivate a healthy gut microbiome than taking supplements or eating a particular kind of food. Most specialists do not recommend, for example, eating yogurt as an effective way to ingest probiotics. Most yogurts (including those with live cultures) don't have enough CFU's/serving to make a difference, and don't have a diversity of active cultures.
By a healthy diet, they mean a diet rich in plant-based foods, low in processed foods, and (using the average Western diet as a basis) decreased amounts of red meat, high-fat food, and sugars.
In other words, a probiotic is not proven or even likely to help you, whereas a healthier diet is.
Of course, you should seek the opinion of a doctor for your digestion problem. In the meantime, a food/symptom diary is a good idea. There may be a food allergy or sensitivity at the root of your problem, and a food/symptom diary could help determine that.
Decreased Diversity of the Fecal Microbiome in Recurrent Clostridium difficile—Associated Diarrhea
Human nutrition, the gut microbiome and the immune system
Diet-Microbiota Interactions and Their Implications for Healthy Living
Gut Microbiota in Health and Disease <- Excellent (and long) review article.
The Impact of the Gut Microbiota on Human Health: An Integrative View