Experience 6 Months as SDE at a mid size startup

INTERVIEW ROUNDS

OA
Had 2 questions to be solved in 1 hour 30 mins. I dont remember the questions as I gave the OA about 5 months back.

ROUND 1 (Hiring Manager)
Started with introduction and then some LP questions. He asked basic DS things like how Hashmap works etc. Then jumped on to the DSA problem. It was one of the very popular stack problem. I solved the question with expected T.C.

ROUND 2 (Technical)
This time, there were two interviewers and one was probably shadowing. It started with basic introduction and some LP questions. Then he straight jumped to the DSA problems.

Problem1 String based question to find substrings occurence available on leetcode. Solved this in time and with expected T.C. He wanted me to optimise it more to using Rolling Hash technique. I did not know about this technique. Searched for the question on leetcode and found the solution. It was same as the solution I proposed and coded. Dont know what more optimisation he expected even though at the end he said he was satisfied with my solution.

Problem2 Only 12 minutes left in the interview and second question given by the second interviewer. It is LC Hard problem on graph based on Trojans algo. I did not know about algo. I gave an approach and explained it. Interviewer was not satisfied and gave me 3-4 testcases to dry run on my approach and it seemed to work fine and give correct result. Interviewer then asked me to code it which I did in like 2-3 minutes. He/she was happy with my speed to code and asked the other interviewer if he/she wanted to add something who then pointed out a testcases where my approach would not produce the correct output, but there was no time left. They asked me if I wanted to ask something and the interview ended.

Round 3 (Technical)
Again started with introduction and 1-2 LP questions. Then straightaway jumped to DSA problem.

Problem1 Very popular graph question which I solved in 15 minutes using DFS and recursion. He asked me to do it without recursion and I did that. Asked me about other graph traversals and told him about bfs. Asked how I would do bfs without recursion and explained him the queue solution. He was happy and satisfied.

Problem2 PriorityQueue and Sorting based question. Solved this in no time and told him the T.C and S.C. He asked me about internal working of priority queue and asked me to define a few comparators which I did. He was happy and satisfied with both my solutions. I then asked him about my interview performance to which he said that he found no negatives and was fully satisfied with my performance.

ROUND 4 (BAR RAISER)
Interviewer was very friendly and told me that he will be taking notes throughout. He started with LP questions for the first half of the Interview and then gave me a Coding problem which I coded in given time. He seemed satisfied with my performance.

It has been almost 15 days since my last round but I haven't heard back from the recruiter since then. I tried reaching out to him via mail, but got no response. Can someone please tell me what I should be doing in this case now?