If you dont learned p6-F3 tense,you will find it hard in F4-F5 tense.If you are very poor,you need a helping hand to bring/ guide you to better position .like me.The form of a verb which tells the time on the past(the present,the future)tense=meaning TENSE!
I am not sure if I can give you a helping hand as I have been helping a handful of students and the situations of some of them are quite similar to yours. You may drop me a line.