I wanna [粗魯沒教育之所謂] Want have some Dessert (我想要吃些點心 I Would Like to have Some Dessert)

I'm allergic to egg and milk; therefore, I can't eat dessert too much.(我對蛋和牛奶過敏,以致於我不能吃太多)
Because Most of desserts them [正宗英文不許重復, 除非是雄辩, 即默示读者是笨蛋] are made of from [是制做而不是] eggs [不是只用一粒而成]and milk.(大部份的點心都是蛋奶做成的)
Occasionally,_I will just have some a taste. (偶爾我會吃一些)

I can't stop myself in missing how tasty they were since I had enjoyed them last week.(上週甜美的滋味讓我難以忘懷)

It's hard to imagine the terrible feeling of having allergic symptoms.(很難想像吃完後過敏的不適)
I really wanna want have some dessert! (我真的很想吃些點心)

American English Corrections

I Wanna Have Some Dessert (我想要吃些點心) In an informal setting, you can say "wanna" with friends, etc. in American English; otherwise, you should say "want to" instead.

I'm allergic to eggs and milk; therefore, I can't eat desserts too often

(我對蛋和牛奶過敏,以致於我不能吃太多)

Because most of desserts are made of or "from" eggs and milk.(大部份的點心都是蛋奶做成的)

Occasionally, I will have a little taste. (偶爾我會吃一些)

I keep missing how tasty they were when I enjoyed them last week.(上週甜美的滋味讓我難以忘懷)

It's hard (for you) to imagine the terrible feeling of (having) an allergic reaction.(很難想像吃完後過敏的不適)

I really wanna or "want to" have some dessert (我真的很想吃些點心)

I want to wanna have some dessert (我想要吃些點心)

I'm allergic to egg and milk; therefore, I can't eat many types of dessert too much.(我對蛋和牛奶過敏,以致於我不能吃太多)
Because most of desserts are made from of egg and milk.(大部份的點心都是蛋奶做成的)
Occasionally, I will have  a little some taste. (偶爾我會吃一些)
I can't stop missing remembering how tasty they were since I enjoyed them last week.(上週甜美的滋味讓我難以忘懷)
It's hard for you to imagine the terrible feeling of an allergic reaction symptom.(很難想像吃完後過敏的不適)
I really wanna want to have some dessert(我真的很想吃些點心)