A little help trying to conceive

Laurynn
Hi!
​We have been trying for 3 years. Only now has it started to worrie me somthing may be wrong?? As we have had no luck so far. 
​I'm trying to get my head around my ovulation day, has anyone got any tips on how to know which day is 'D' day!! 
​And are there any tablets that can help me along??
​Thanks laurynn x