How can one get rid of obsessive thoughts (waswas) and the frequent discharge of semen, which prevent me from performing prayer regularly and in a state of purity?

We ask Allah to remove the waswasah (whispers of Satan), and it can be overcome by benefiting from Fatwa No. 59951. As for the discharges, if it is merely a doubt, then one should disregard it. It appears to be vaginal discharge, which is pure but nullifies ablution. If its flow is continuous, the woman performs wudu for each prayer, and her ruling is that of a woman experiencing istihadah (non-menstrual vaginal bleeding). If it stops, she waits for it to cease, purifies herself, and prays.

However, if you are certain that the discharge is maniyy (seminal fluid), then ghusl (ritual bath) is not obligatory unless it is accompanied by desire or caused by it, according to the majority of scholars. If maniyy is constant, ghusl is not necessary according to the majority, but wudu must be performed for each prayer with the intention of making the prayer permissible, and wudu for an obligatory prayer is not valid before its time enters.

You must increase in repentance and seeking forgiveness for missing prayers. The majority of scholars hold that it is obligatory to make up missed prayers that were not during menstruation, and even if you were excused due to ignorance of the ruling, this excuse does not waive the obligation of making up the prayers according to the majority. However, the obligation to make up is waived due to ignorance according to some scholars, such as Ibn Taymiyyah.