Bd timing and chances of conceiving

I don't know exactly when I ovulate I can't figure it out right my app is telling me something different to what my other app used to tell me and I can't work it out from my cycle lengths etc I know I have a 24 day cycle length and 4 day period so I have roughly caculated it as I ovulate day 10 but I'm not sure I had a period on 14th December and baby dance on the 14th the same day as my cycle started which I know it's unlikely to get pregnant from if you baby dance in your cycle my ovulation for this month was any where from 23rd - 26th december i think but im not sure my next cycle is on the 7th January me and my bf baby danced twice once yesterday but we didnt finiah baby dancing until after midnight so you coukd class it as yesterday and today and we baby danced at half 5 this morning we have only just started trying for a baby but I'm frustrated as I'm not sure when I ovulate and I need to know that to time baby dancing better to improve my chances of conceiving