Should I up my calories?

OK, so I started working out again and eating like a horse in early November. I was 150 pounds, about 5'10". I had been eating around 1200 - 1500 calories per day. My trainer had me up my calories to 2500 per day, 150 grams of protein, and 96 oz. of water. Things have been going well, and I'm up to around 175 pounds. Lately, I don't feel as pumped full of energy at the gym, and although I'm still putting on muscle and moving up on weights, it doesn't feel as effortless. Is this just a normal thing after three months of a program like this? Should I be upping my calories now that I've put on more muscle mass? Thanks for your insight!

UPDATE: Maybe I wrote this too soon! I just came back from an awesome shoulder workout. I went to NYC last week and had the flu first day I was there. I thought I was fully recovered, but maybe I was still on the mend. Hopefully, I'm back to rockin' it at the gym! Thanks for your suggestion, Potter. I'll give it a try!

I think maybe you should try upping your simple sugars before you go to the gym...not crappy sources but eat a couple bananas or apples on top of your normal diet to see what happens...I don't think it will give you much bulk but you should get a bit of an energy boost

2 bananas before your workout will make you feel good.