4 time mother hitting plateau

Hello,

I'm a 4 time mother. My youngest is 2.5 months old. I've actually done really well for having a newborn and have lost all the weight I put on during my last pregnancy. However, I have 25-30 pounds hanging on from my previous 3 pregnancies and I've hit a plateau that I can't bust. I'm 160 right now, but just less than a week ago I thought I went down to 155. It must have been a dream because I haven't seen that number again. I've been 160 for 2 months now. Running 2-4 times a week for more than 1.5 miles each time. Eating mostly vegetarian diet, but have sweets whenever I do splurge. I am fairly balanced, but I can't budge the 160 mark. Please tell me it won't be like this forever!!!!!