Custom controller not able to jump and find ground

Hey guys- I created my own kinematic character controller which can move, snap to the ground, and jump smoothly. However, in order to get the jumping smooth, I needed to unground the character and apply a Sin lerp.

As a result, if a character jumps and intercepts a slope, he continues jumping through the slope to the ground (since he is ungrounded at that point). Does anyone know how I can get my Gravity/grounding method and my jump method working together?

Code (CSharp):

1.   private void FixedUpdate()
2.     {
3.         Movement();
4.  
5.         Gravity();
6.  
7.         Jump();
8.  
9.         FinalMovement();
10.    
11.     }
12.  
13.     private void Gravity()
14.     {
15.         boxSize = Vector3.one * .4f;
16.         boxPos = new Vector3(transform.position.x, transform.position.y - transform.localScale.y, transform.position.z);
17.  
18.         isGrounded = Physics.CheckBox(boxPos, boxSize, Quaternion.identity, excludePlayer);
19.  
20.         if (!isJumping)
21.         {
22.             if (isGrounded)
23.             {
24.                 currentGravity = 0;
25.  
26.                 Ray ray = new Ray(transform.position, Vector3.down * 2);
27.                 RaycastHit hit;
28.  
29.                 if (Physics.Raycast(ray, out hit, Mathf.Infinity, excludePlayer))
30.                 {
31.                     if (hit.distance < 2)
32.                     {
33.                         Vector3 groundSnapPosition = new Vector3(transform.position.x, hit.point.y + transform.localScale.y, transform.position.z);
34.                         transform.position = groundSnapPosition;
35.                     }
36.                     else
37.                     {
38.                         currentGravity = -gravity;
39.                     }
40.                 }
41.             }
42.             else
43.             {
44.                 currentGravity = -gravity;
45.             }
46.         }
47.     }
48.  
49.     private void Jump()
50.     {
51.         //reset when we press spacebar
52.         if (jumpRequested && isGrounded)
53.         {
54.             unGround = true;
55.             jumpStartPos = 0;
56.             jumpEndPos = jumpDistance;
57.             currentLerpTime = 0f;
58.             jumpRequested = false;
59.             isJumping = true;
60.         }
61.         else
62.         {
63.             jumpRequested = false;
64.         }
65.  
66.         if (isJumping)
67.         {
68.             //increment timer once per frame
69.             currentLerpTime += Time.deltaTime;
70.             if (currentLerpTime > lerpTime)
71.             {
72.                 currentLerpTime = lerpTime;
73.                 isJumping = false;
74.             }
75.  
76.             //lerp!
77.             float perc = currentLerpTime / lerpTime;
78.             perc = Mathf.Sin(perc * Mathf.PI);
79.  
80.             prevJumpHeight = jumpHeight;
81.             jumpHeight = Mathf.Lerp(jumpStartPos, jumpEndPos, perc);
82.             jumpDelta = jumpHeight - prevJumpHeight;
83.  
84.         }
85.     }
86.     private void FinalMovement()
87.     {
88.         Vector3 movement = new Vector3(transform.position.x, transform.position.y + jumpDelta - currentGravity, transform.position.z);
89.         transform.position = movement;
90.     }