Weight loss while TTC

Sarah • Mom of 2 (ages 14&11). TTC #3 since Jan 2014 with new hubby (his first). #1 miscarriage November 2015 :(
Anyone attempting to count calories / loose weight and actively TTC?
​I'm slightly overweight but I'm 31 and don't want to run out of time. 
​I have two older children from previous marriage (13 & 10) but I'm nervous now being older and any issues my new OH may have (he doesn't have any children).
​I'm wondering what is a healthy daily calorie intake for TTC and when I should up my calories when/if I get my BFP and to what. Any advise??