Why is he so wishy-washy about having kids?

So, Ive been with my Fiance for 2 years. On the second date we were both deleting people off our phones and he went home and tokd his parents he found his wife. He has treated me better than any man has and I love him so much, hes great. We have had a business together for a year and were doing really well financially which is great. Since we started dating we have had conversations about having children. He has told me he wants children, it means a great deal to both of us to have a family. But fir the past year anytime I bring up children or starting a family which I dont do often he gets uncomfortable. Ive had two miscarriages with him.( i have an auto ammune disease which makes ut hard to go gull term with pregnancy) bith times when I told him I was pregnant he absolutely flipped out saying he isnt ready financially and we cant have kids yet

. Which uf I were already pregnant you cant really change that you know. But he would het so upset.. i dont know if he is scared if the unnown or what but uts freaked me out enough when I di get pregnant again I dont know if I want to tell him right away.. which feels wrong. So what I dint understand is if he wants kids and were financially stable why would he freak out so much.. i mean im 28 and hes 31 i dont want to wait toi much longer for kiddos. Whats yalls yalls thoughts? He isnt cheating, were happy together, weve fot a home big enough for kids..