Hi, sorry to hear about your condition. Glad you reached us.
Coming to your concern, first of all it will be better to completely avoid dairy products and it is causing trouble in your digestive system. There are people who cannot tolerate milk or milk products and it is absolutely normal.
Taking probiotics will help your diarrhea to subside.
Take Antacid like
pantoprazole or
Ranitidine half an hour before meals. Post meal if you feel bloated abdomen with lot of gas, effervescence antacid will give some relief.
Avoid Spicy oily diet and food which are causing
indigestion for you.
Take small small meals frequently, don't keep your stomach empty for more than 3-4 hrs.
Take light meal /dinner at night.
Drink plenty of fluids.
Following above measures will help you in reducing gastritis/ acidity problem and diarrhea.
Now, coming to your irregular menstrual cycle, there are conditions like
thyroid dysfunction,
polycystic ovarian disease, low heamoglobin, certain medications, stress etc which causes irregular cycle. I would suggest you to go for proper investigation like
complete blood count, thyroid profile,
Ultrasound abdomen to know the exact diagnosis. Once the cause has been treated, menstrual cycle will become regular and there won't be problem in conceiving again.
Hope I have provided you the necessary information you wanted.
All the best, take care.