I'm trying to work out when was my most fertile time to fall pregnant, I came on my period last month the tenth December so when do you think the best time I could have fell pregnant, I think I'm pregnant

How long are your cycles? The average ov. Timing is 12-14 days from the first day of your period (for a 28 day cycle) If you are on this exact schedule, then your most fertile days would have been around the 22nd- 24th of Dec. however since every woman is different and so are their bodies, and as such a large portion of us have different lengths of cycles, and ovulate at different times. Some women ovulate at the beginning of their cycle, some at the end, and some even while on their periods. The only ways to know for sure when you ovulate, would be opks(ovulation predictor kits) monitoring your cm (cervical mucus) and your bbt(basal body temp). Its also important to remember that sperm can live inside of you for up to a weeks time, so you wouldn't have nescisarily had to have sex on the day you ovulated, as you could get pregnant from having sex several days before you ovulated.

Baby born 29 March 2010 so when did I fall pregnant?

Pregnancy Calculator for Conception Gestation & Due Dates : American Pregnancy Association

Try this. Just forfun though.