Sorry to hear about rocky times. Sounds mostly like a communication problem, as people have said. That's going to demand effort from both of you.
As for how strongly we feel love/feelings, the unromantic answer ( ) is "How can anyone know unless they've been different people at different times in their life? How do you know what another person's feelings feel like?" The closest you can come is how they express them, seeing it externally. Internally...it's a mystery.
However, my opinion is that love is still love, and the feeling itself can be felt in all its intense glory by any type of personality. Its obviousness on the outside is what changes. I've said it plenty of times before, and I don't know whether people will believe me, but personally my answer is "Yes! ISTJs can feel very strong emotions." Most of the time it's true that my emotions stagnate around a center line, not up or down too much in either direction. But for all those times I've felt that weird, bewildering, exciting feeling of infatuation or heartbreak or like I'd have to lie down for a while to let built-up nervousness and anxiousness for a girl subside, or every night I couldn't sleep from an adrenaline-like rush when discovering a mutual crush, or every night I couldn't sleep because I worried that I totally destroyed the way she feels about me--That those were all "inadequate emotions" hurts quite a bit, especially if it were coming from my girlfriend.
(Feel like a vulnerable idiot for typing the above. Even though it's true.)
And it could be "just me," but I hope you understand. I think it's important to keep talking to him about how you guys feel about every little thing, and think about the way you see those things/actions/words. Try to understand through his language (and hopefully he will through yours, too).