Am I doing too much exercise?

Hi there (i know its a long post but please stick with it - i need help!!)

I was wondering if anyone could give me some advice on whether the fact that i'm doing too much exercise is actually preventing me from loosing weight.

To cut a long story short (well as short as possible) I started running 7 years ago when i was 24 (now 31). I LOVE running, soon did it everyday, miles and miles, ran marathons, half marathons - even won various races including a marathon. The added bonus was i lost a ton of weight and got down to about 105lbs (too small but i was very fit and efficient). I watched what i ate but pretty much could eat whatever i wanted.

As i've got older my weight has crept up despite still running - i have tried doing other forms of exercise Spin, cycling, cross-fit, kettle bell workouts, interval training, tabata, weights etc but nothing seems to be working at all and now my weight is back to what it was before i started running around 140lbs. I am not comfortable at this weight and i really want to feel efficient and look as atheletic as possible especially when running.

I was wondering whether my body could be too use to cardio and if counting it down would help. I currently do about 90mins everyday of various forms of exercise. I know i don't eat enough for the amount of exercise but i tried increasing my calorie intake and still my weight continues to go up.

Does anyone have any advice or gone through a similar thing?

Any help would be much appreciated please.

Chez