Upping protein and fats has helped me in your situation. I used to eat a lot of oatmeal, but I've found substituting eggs for breakfast has helped a lot in keeping my body weight where I want it to be. I probably don't eat as cleanly as you do (just a guess because I don't eat all that cleanly), so this might not make as much of a difference for you.
I'd still say you're probably going to be better served by lifting in the 148s. If you're just starting out in powerlifting, you're going to naturally gain some weight over the course of the first couple of years of powerlifting, even if you've been lifting before. I think you risk holding your long-term development as a lifter back by trying to stay (or get) into a weight class you're already out of. My advice would be to lift as a light 148 in your first meet. After that, eat to support your training and you should eventually fill that class out, in a good way.
Eight years ago I was a light 242, now I fill the class out and my total is up nearly 500 pounds. I wasn't new to lifting when I started either, I'd been training for strength for about 5 years before that. I'm really glad I didn't try to make the 220s when I started lifting as I truly believe it would have held me back in the long run.
Good luck with whatever you decide to do and welcome to a wonderful sport.