Hello Paynviet,
The average time for a healty, fertile coupe in their 20s to conceive is 6 months, so I wouldn't worry yet - not conceiving in 4 months is still perfectly normal. Eating healthy is great if you do become pregnant, but there is no evidence it helps with conception. Here are a couple thoughts:
- being overweight or very thin decreases your likelihood of conceiving, so being a healthy weight is important
- try using a sperm-friendly lubricant (like Proseed - you can get it at most drug stores). I credit this with helping me conceive quickly (before I became infertile due to age)
- you can use ovulation predictors to see if you are ovulating, but these can be expensive. Alternatively, just "BD"ing every other day in the middle of your cycle is sufficent (there is some evidence that every other day is even better than every day)
- Be sure to take folic acid supplements to prevent spinal cord defects (including a fatal birth defect called anencepahly in which most of the baby's brain never develops). You need to take these before conception to reduce your risk.
- if you are older (35 and up), and you have the resources, seek medical advice if you don't conceive in six months or so.
Best of luck,
Mel