Why Did I Gain Weight on MFP and lifting heavy????

Probably one of two things going on here: scale problems or muscle gain. Scales can be calibrated differently, so the number you see on one is not the same as what you'd see on another. As for not gaining muscle while eating at a deficit, I'm not sure. All I know there is that muscle definitely weighs more than fat, but burns calories faster. Actually, your metabolism may be a little screwy since you started gaining muscle. Your body is able to burn faster, but it thinks it's not getting enough calories, so it goes back to storing. I feel like many of the threads I've seen here to do with lifting or strength training in general encourage upping your calorie intake when you add strength training, to balance everything out.

You mentioned that some of your clothes are fitting better. Have you taken measurements? Particularly as you start toning up, those numbers will be a better indication of your size than the one on the scale. Comparison pictures are another good way to judge. There's a thread in success stories, "125 lbs no exercise compared to 135 lbs weight lifting," that demonstrates this perfectly. Check it out; I think it'll help you to rethink your progress.

Hang in there! It sounds like you're doing amazing.

Are you sure you weighed 150 before or is that just what you thought you weighed? Do you weigh yourself regularly on the scale at work? If you normally weigh without clothes at home and weigh in clothes at work, there is going to be a difference in those numbers. You can't really use different scales and different circumstances to measure progress, and if you're not weighing on a pretty regular basis, you don't really have any way of knowing how much of that suspected increase is water/waste as opposed to muscle or fat.

You said your clothes are fitting better, so you probably have not gained much, if any, fat.

Also, are you sure you are tracking your calories accurately? Is it at all possible that you are eating more than you realize because you are leaving out oils, condiments, sauces, random pieces of candy, extra creamer in your coffee, etc.?

So you're smaller and look better... And you're upset why?

Maybe you should rethink your measurements of success.

Different scale. Fully clothed. At work (so probably after eating breakfast.) Possible water retention. TOM by chance? There are so many factors here.
'Sides, as others have said, if you are losing inches why do you care what the scale says? I gained 8 lbs in a week the first week I started this journey but lost 6 whole body inches. Don't ask me to explain how that works, I don't know but I don't care. I am smaller, that's good enough for me.