Oh, and, three responses to the OP if you are still reading this:
1/
If you are training for a 13.1-mile race, you should definitely be running more than 2-3 miles a day. Probably about twice that much (if your goal is just to *finish* the half marathon), say 25 to 35 miles/week. If you're just starting, build up to it.
If you are varying your tempo -- some fartlek/speedwork, some normal tempo running, and occasional sprints on the track (a couple times a month) -- then you can knock the mileage down a bit.
2/
Your two goals (being "toned" and running a 13.1-mile road race) are going to butt heads after a while.
Endurance work, if you get too serious about it, will have pernicious effects on the "toned"/"full" look of muscles. (Long story short: More cortisol, fewer androgenic and estrogenic hormones.) It'll make you long, lean, sinewy, and whip-like -- take a look at some marathon runners -- but it's not the best route to a beach bod.
For women, the best route to a beach bod is disciplined (your diet should be on point), but lazy (you honestly don't need to work out very much). Lazy is always a good thing, if you ask me.
3/
Make sure you're getting monthly bloodwork, especially thyroid tests (t3, tsh, and t4).
Basically, endurance training can f*** with thyroid function in women, a LOT more than in men. Who knows why -- it's probably an evolutionary adaptation, to keep you from losing too much fat to have the bebehs -- but, it is what it is.
If your thyroid levels are tanking, cut back the training, and/or find a doctor who is far-seeing enough to write you a temporary rx for some thyroid meds. Or else you risk turning into a zeppelin as soon as you cut back the mileage.
Good luck.